
Class JrEs.5:: 

Book__iif£L. 



COPYRIGHT DEPOSIT. 



ELEMENTAKT ELEOTEO-TEOHNIOAL SEKIES 

ELECTRIC STREET 
RAILWAYS 



BY 

EDWIN J. HOUSTON, Ph. D. 

AND 

A. E. KENNELLY, Sc. D. 



Second Edition, Enlarged 



NEW YORK 

McGRAW PUBLISHING COMPANY 

1906 



UBMRYafCONeilESS 
Tim C«9let Reoalmi 
NOV 5 1906 



Capyrt^Ejitay , 



XCapyrtMt Entry 

9U8S A MCb.Nt. 
/(oO 03^ 
COFY B. 






Copyright, 1906, by the 
MgGRAW publishing COMPANl 

T^Ew York 



^PREFACE. 



Even in the annals of applied electricity^ 
where phenomenal growth has been a lead 
ing characteristic, perhaps nothing has 
equalled the rapidity with which the elec- 
tric railroad has come into actual use as a 
necessity of our everyday life. In our 
more populous cities, not only has electric 
traction almost entirely displaced the 
street car, but, where it has paralled steam 
railroads, it has proved, for suburban traf- 
fic, a rival which is every day becoming 
more and more formidable. 

In the popular mind so much mystery 
surrounds the electric railroad, that it is 
generally considered practically impossible 
for the ordinary individual to obtain a 



IV PREFACE. 

clear conception of its method of oper- 
ation. The authors have prepared this 
little volume of the Electro- Technical Series 
in the belief that these difficulties are ap- 
parent rather than real — that it is quite 
possible for the general public to obtain a 
fairly intimate knowledge of the leading 
principles of electric traction without any 
previous knowledge of electrotechnics. 

It is a matter of necessity rather than 
choice, at the close of this nineteenth cen- 
tury, when electric traction has become so 
nearly universal, that a knowledge of the 
main principles concerned should be gener- 
ally accessible, without special training, 
and more especially is this desirable on the 
part of those, now an exceedingly exten- 
sive class, who are connected in some way 
or other with such enterprises. 

The authors present this book to the 
general public hoping that it will meet the 
need above referred to. 



PREFACE. 



PREFACE TO THE THIRD 
EDITION. 



The recent development of the electric 
railway to passenger traffic, as exemplified 
by the advent of the electric locomotive 
on steam-railroad tracks, has called for 
special attention on the part of the electri- 
cal engineer and of the reading public. 

The authors hope that this enlarged 
new edition may meet with the require- 
ments of the subject in its most recent 
development. 

May, 1906. 



CONTENTS. 



I. Introduction, .... 1 
11. Early History of the Electric 

Railway, .... 8 

III. Elementary Electric Principles, 15 

IV. The Motor, . . . . . 67 
V. Cars and Car Trucks, . . 97 

VI. Electric Lighting and Heating 

OF Cars, 134 

VII. Controllers and Savitches, . 154 

VIII. Trolleys, 204 

IX. Trolley LmE Construction, . 219 

X. Track Construction, . . . 242 



Vlll COl^TENTS. 

CHAPTER PAGE 

XI. Electrolysis, . . . . 249 

XII. Switchboards, .... 262 

XIII. Generators and Power Houses, 279 

XIV. Operation and Maintenance, . 297 
XV. Storage Battery System, . . 307 

XVI. Electric Locomotives, . . 323 

XVII. High Speed Railroad Service, . 343 

Index, 351 



ELECTEIC STEEET EAIL- 
WAYS. 



CHAPTER L 

IlS^TEODUCTIOlSr. 

The introduction of the electric street 
railway naturally caused mucli wonder- 
ment. There seemed at the first some- 
thing weird in the possibility of propel- 
ling a heavily loaded vehicle, from place to 
place, without any apparent motive power, 
and, even at the present time, there remains 
no little astonishment in the mind of the 
casual observer as to how the electric 
agency can silently, yet surely, find its way 
from a power house, in some remote corner 
of a city, through an intricate maze of 



2 ELECTRIC STREET RAILWAYS. 

streets and turnings, and propel eacli car 
as thougli the latter were under the guid- 
ance of a familiar spirit. The wonder 
grows, when it is pointed out that the 
electric current not only has to find its 
way from the power house over the 
trolley wires to the cars, wherever these 
may be, but has also to return to the 
power house through the track and 
ground. 

It is, unfortunately, too true that the 
real nature of electricity remains un- 
known, even in this electric age. For this 
reason, there has, perhaps, existed, in the 
minds of the public, too marked an unwill- 
ingness to attempt even to form ideas as 
to the laws wdiich control electric opera- 
tions. But it should not be forgotten, 
that although our knowledge of the exact 
nature of electricity is imperfect, yet 



INTRODUCTIOIT. 3 

our knowledo;e of the manner in whicli it 
operates, that is o£ the laws which control 
it, is surprisingly definite. Indeed, so far 
as the laws which govern the flow of 
electric currents through conducting paths 
or circuits are concei^ned, our knowledge 
is even more definite than of the laws 
which control the flow of water or gas 
through pipes. In fact, as we shall 
subsequently see, a remarkable analogy 
exists betweeu the law^s which govern the 
flow^ of gross matter in the fluid state, that 
is as liquids or gases, and the laws which 
govern the flmv of electricity. 

It may be well, therefore, before pro- 
ceeding further with the general discus- 
sion of electric street railways, to outline 
briefly the points of similarity between 
the flow of liquids and the flow of elec- 
tricity. 



4 ELECTEIC STREET RAILWAYS. 

Perhaps no better illustration could be 
given, concerning some of the laws of 
liquid flow, than that taken from the dis- 
tribution of water through the mains and 
pipes of a large city. Here, as is well 
known, a supply of water is provided in 
a reservoir, at a high level or pressure. 
Pipes or mains connecting with this reser- 
voir extend beneath the streets to all por- 
tions of the city that are to be supplied 
with water. No difficulty will be experi- 
enced in understanding how, if no obstruc- 
tion exists in the pipes, the water will 
flow through them from the reservoir and 
escape through any outlet at a lower level. 

Let us now examine the network of 
pipes connected with a reservoir in a 
system of municipal water distribution. 
It is evident that the object of such a 
system is to supply the houses or other 



INTRODUCTIOIS'. 5 

buildings either with water, or with the 
power the water is capable of exerting. 
For this purpose two sets of pipes are 
provided; viz., 

(1) TliQse connected immediately with the 
reservoir and intended to carry the water. 

(2) Those connected to the consumers' 
waste pipes. 

The latter are connected intermediately 
Avith the sewer system, and ultimately 
with the lake,"i'iver, or ocean into which 
such sewer system discharges. 

Between the reservoir and the river, it 
is evident that the flow of water through 
the pipes is due to gravity, the water find- 
ing its way through the pipes in obedience 
to the law of liquid levels. After the 
river has been reached, and the water is 
ultimately discharged into the ocean, thus 
reaching its lowest level, some means must 



6 ELECTRIC STREET RAILWAYS. 

be provided for causing the water to rise 
against the force of gravity and fill the 
reservoir afresh. This energy is received 
from the sun during the evaporation of 
the w^ater when it passes into vapor and 
rises into the atmosphere. On the loss of 
the heat so received the water again falls 
under the influence of gravity, and returns 
to the reservoir. 

An analogy between the preceding 
system of water distribution through the 
pipes of a city, and a system of electric 
distribution through the trolley wires, is 
evident. Here, as we shall more fully see 
in a subsequent chapter, an actual differ- 
ence of electric level exists, whereby an 
electric source, or generator, at the power 
house, causes the electricity to flow 
through all the conducting outgoing trol- 
ley wires from the higher electric level 



INTRODUCTIOIS'. 7 

of the generator to the cars. In passing 
through the cars, it may light and heat 
them as well as drive their motors. On 
leaving the cars it flows through the 
ground back again to the generators in the 
power house. In this latter part of its cir- 
cuit or path, an analogy is to be found 
between the discharge of the water to 
the lower level of the ocean, prior to 
its passage back again to the higher level 
of the reservoir. _ 

Although we have thus traced the anal- 
ogy between liquid flow and electric flow, 
and have shown that the same general 
laws apply to each, yet it must be remem- 
bered that this is an analogy only; and 
that electricity is not believed to be a mate- 
rial fluid. The analogy is, however, useful, 
and will aid the student in forming practi- 
cal conceptions of the electric circuit. 



CHAPTER II. 

EAELY HISTORY OF THE ELECTRIC RAILWAY. 

The broad idea of propelling vehicles 
by means of the electric cuiTcnt appears to 
have suggested itself to the minds of 
inventors at an early date. As long ago as 
1835, Thomas Davenport, of Vermont, con- 
structed a working model of a car pro- 
pelled by an electric motor of his own 
invention. In 1838, Robert Davidson, of 
Scotland, also produced an electrically pro- 
pelled car. Both of these early cars 
derived their propelling current from 
voltaic batteries carried on the car. 

The idea of taking the electric current 
required for the propulsion of the car from 

8 



HISTORY OF THE ELECTRIC RAILWAY. 9 

conductors laid alongside the track was 
not conceived until a somewhat later date ; 
namely, in 1840, Avhen Henry Pinkus 
obtained letters patent in Gi'eat Britain for 
a method of propelling carriages either on 
railroads or on ordinary highways. This 
patent discloses among other things, the 
broad idea of takino; electric current from 
conductors, in contradistinction to employ- 
ino; batteries on the car. 

Space will not permit us to enter in 
detail on this portion of the early history 
of the electric railway. It will suffice to 
say, that in 1851, Professor Page of the 
Smithsonian Institution devised an electric 
locomotive which he ran on a track at the 
rate of nineteen miles an hour. This 
locomotive, like those of Davenport and 
Davidson, carried the voltaic battery 
required for its propulsion. About the 



10 ELECTRIC STREET RAILWAYS. 

same time Professor Moses G. Farmer also 
devised an electrically propelled car. 

All these early discoveries belong to the 
type of ideas that are born too early to 
come to fruition. Practically the only 
electric source that was known at this date 
was the voltaic battery, which is incapable 
of commercially producing the powerful 
electric currents required for the propul- 
sion of street cars. It was not until the 
dynamo-electric machine was perfected 
that electric car propulsion became com- 
mercially practicable. 

The advent of the dynamo-electric 
generator, therefore, marked the second era 
in the history of electric railway develop- 
ment. The low cost at which this elec- 
tric source can furnish powerful currents 
attracted the attention of inventors, who 



HISTORY OF THE ELECTRIC RAILAYAY. 11 

long before had recognized the part elec- 
tricity was destined to play in electric 
locomotion. Consequently, this era of the 
history of the electric railway contains 
many inventions. 

It is not our intention to enter into any 
discussion as to the claims of the various 
inventors to priority in any of the more 
salient features of the art of electric trac- 
tion. We wiir content ourselves with a 
brief account only of some of the work 
accomplished at this time. 

One of the pioneers at the beginning of 
this era in the history of the electric rail- 
way was George Green, who devised a 
road on a plan similar to that of Farmer, 
but containing many marked improve- 
ments. Green, who was poor, experienced 
difficulty in s;etting his patent interests 



12 ELECTRIC STREET RAILWAYS. 

attended to. Being placed in interferences 
with other applicants^ a patent was not 
issued to him until the last month of 1891, 
although applied for as early as 1879. 

Passing by a number of inventors who 
devised electric locomotives of various 
types, Ave come to the electric railway of 
Siemens and Halske, which was put into 
actual operation at the Industrial Exhibi- 
tion of Berlin in 1879. As in all electric 
railways belonging to this era, the motive 
power was derived from dynamos located 
at a central station. The current was 
delivered to the motor by means of a slid- 
ing contact under the locomotive, rubbing 
against a rail placed midway between the 
two track rails. 

Very little was done in electric railways 
in the United States^ prior to 1883. It is 



HISTORY OF THE ELECTRIC RAILWAY. 13 

true that in 1880 some work was under- 
taken by Edison wliich resulted in the 
erection of an experimental track, and that 
prior to this date; namely, in May, 1879, 
Stephen D. Field had done some experi- 
mental work which he protected in the 
United States Patent office by a caveat. 

In the meantime inventors in other 
countries had by no means been idle. 
The honor of establishing the first com- 
mercial electric street railway appears to 
belong to Germany, where the Lichten- 
feld line was put in operation in 1881. 
Another road was opened at Portrush, in 
the north of Ireland, in 1883, the dynamos 
being in this case driven by water power. 

Among early railways operated in the 
United States was one constructed and 
put in operation by Vanderpoele, at the 



14 ELECTRIC STREET RAILWAYS. 

Chicago State Fair during two montlis 
in 1884. A short line, located on one 
of the piers on Coney Island, N. Y., was 
operated during the summei' season of 
1884. The year 1884 also saw the first 
public electric street railway in operation 
at Providence, R. I., and the first practical 
trolley road was that in the suburbs of 
Kansas City, Mo., in the same year. 

The advantages possessed by electric 
traction over ordinary methods, such for 
example, as horse cars, are so great, that 
while in 1884 the first electric road was 
installed in the United States, there were, 
in 



1889, 50 


roads with 100 miles of track. 


1890, 200 


1,200 '' 


1891, 275 


2,250 " 


1894, 606 


7,470 " 


1895 (July), 880 


" 10,863 '' 



CHAPTER HI. 

ELEMEISTTARY ELECTRIC PRINCIPLES. 

Before proceeding to a consideration of 
purely electrical matters it will be advis- 
able to discuss briefly the general subjects 
of work and activity. Suppose, for 
example, that a street car is being drawn 
at a steady rate of 5 miles an hour by 
a horse alono; a level track. Thjn it is 
evident that the horse has to do work in a 
mechanical sense, in order to maintain the 
motion. If the car could be so constructed 
that there was absolutely no friction in its 
journal bearings, and, moreover, if the road- 
bed could be so constructed that there 
were no inequalities in its metal surfaces, 

15 



16 ELECTRIC STREET RAILWAYS. 

and no friction between tlie wheels and 
the rails, then no work would have to be 
expended in maintaining a steady sj)eed 
on a level road ; or, in other words, once 
the car was set in motion, it would con- 
tinue to run at the same rate for an indefi- 
nite period. Under practical conditions, 
however, as is well known, a certain 
amount of friction necessarily occurs and 
has to be overcome. The greater this 
friction the greater will be the amount of 
work which must be expended in order to 
keep the car running. If the road instead 
of being level is on a gradient, then it is 
evident that an ascent of this gradient 
necessitates the expenditure of work 
against gravitational force, in addition to 
the work expended in overcoming friction. 
The heavier tlie car and the greater its 
load ; i. ^., the greater the number of pas- 
sengjers it carries, the greater will be the 



ELEMENTARY ELECTRIC PRINCIPLES. 17 

frictional work and also the gravitational 
work. 

In order to estimate the amount of 
work done in any particular case, as for 
example, in the case above referred to of a 
moving car, reference is had to certain 
ttnits of loorh. It is evident that when 
the car is being pulled by a* rope, the rope 
is subjected to tension, such as might be 
produced by a weight supported over a 
pulley. The harder the horse pulls, the 
greater will be the tension and the greater 
the equivalent weight. Thus a horse may 
readily exert a pull upon its traces of 
400 pounds weight. The greater the dis- 
tance through which the tension is ex- 
erted, the greater will be the work done. 
Thus if a tension of 400 pounds weight 
be steadily exerted upon a car so as to 
draw the latter through a distance of 



18 ELECTRIC STREET RAILWAYS. 

100 feet, then the work done will be 100 
times as great as if the car were only 
drawn under this tension through 1 foot ; 
and, generally, the amount of work, which 
is performed by a tension or pull, is equal 
to the tension multiplied by the distance 
through which it has been exerted, so that 
if the horse continues to exert a pull of 
400 pounds so as to draw the car 100 
feet, the horse will have expended on 
the car an amount of work equal to 
400 X 100 ^ 40,000 foot-pounds. 

The foot-pound is not generally em- 
ployed as the unit of work, except in 
English-speaking countries, and, even in 
such countries, scientific men generally 
prefer the joule^ a unit based on the 
French system of weights and measures. 

/7 

A Joule is of a foot-pound, approxi- 



ELEMEIS^TARY ELECTRIC PRINCIPLES. 19 

mately ; or, one foot-pound may be taken 
as equal to 1.355 Joules. The foot-pound 
is, consequently, roughly one-third greater 
than the joule. If we multiply the 
number of foot-pounds by 1.355, we 
obtain the number of joules within a 
degree of accuracy Sufficient for all ordi- 
nary purposes. For example, when a 
man, weighing 150 pounds, raises himself 
through a vertical distance of 100 feet, he 
performs an amount of work equal to 
100 X 150 = 15,000 foot-pounds in the 
process. The same amount of work might 
be expressed in joides instead of in foot- 
pounds by multiplying the number of 
foot-pounds by 1.355; or, 15,000 x 
1.355 = 20,325 joules. Again, when the 
horse raises a 25,000 pound car along a 
o;radient through a total vertical distance 
of 100 feet, it thereby necessarilj^ per- 
forms an amount of work against gravi- 



20 ELECTRIC STREET RAILWAYS. 

tation, represented by 100 X 25,000 = 
2,500,000 foot-pounds. This amount of 
work might be expressed in joules by 
multiplying by 1.355 — 3,387,500 joules. 

A very important distinction must be 
carefully kept in mind between work 
expended in performing any operation, 
and the rate at wliicli tliat ^vorh is ex- 
pended ^ or, as it is usually called, the activ- 
ity. For example, a man weighing 150 
pounds may raise his weight through 100 
feet, by ascending a flight of staii's, in 10 
minutes, or in 1 minute. Tlie amount 
of work done against gravitation will in 
either case be the same; namely, 15,000 
foot-pounds, or 20,325 joules, but it is evi- 
dent that the effort which the man must 
exert in the two cases, and the relative 
degree of exhaustion which he will 
undergo will be very different. Ascend- 



ELEMENTARY ELECTRIC PRINCIPLES. 21 

ino; the flio'lit in 10 minutes would be 
walking upstairs at a leisurely rate, while 
ascending it in 1 miDute would mean 
running upstairs at nearly full speed. 
The man is obviously ten times more 
active in the second case than in the first ; 
or^ he expends energy ten times faster. 
In other words, he works ten times as fast 
in the second case as in the first. Conse- 
quently, activity may be defined as the 
rate-of-working. 

The unit of activity generally employed 
in English-speaking countries is that based 
on the foot-pound, and is \\\^ foot-pound'per 
second^ so that unit activity is the rate 
of expending 1 foot pound of work in 1 
second. If, for example, a man raises his 

weight of 150 pounds through ^-^^th of a 

foot in each second of time, he expends an 



22 ELECTRIC STREET RAILWAYS. 

amount of work equal to 150 X — — - = 1 
^ 150 

foot-pound in each second ; or, is working 

at tlie unit rate, or with the unit activity. 

As this rate of working would evidently 

be a very small one, in dealing with large 

machines it is more usual to employ a 

unit called the horse-power, which is 550 

foot-pounds in 1 second. Thus, when a 

man weighing 150 pounds, raises his 

weight through 100 feet in 1 minute or 60 

seconds, he will perform 15,000 foot-pounds 

in 60 seconds, or he Avill average a rate 

of working of —~- — ==250 foot-pounds 

250 5 
per second; or, ^— - = —ths horse-power ; 

or, will be working roughly at half the 
rate of a standard horse. If, however, the 
man ascends 100 feet in 10 min^utes, he 
performs 15,000 foot-pounds in 600 sec- 



ELEMENTARY ELECTRIC PRINCIPLES. 23 

oiicls; or, at an average rate of 25 foot- 
pouncls-per-seconcl, that is his activity is 

25 5 

only ^—r = T^TT.ths of one horse-power. 
-^ ooO 110 ^ 



Where the Joule is employed as the 
unit of work, the interiiational unit of 
activity is the joule-per-second ^ or, as it 
is commonly called, the toatt^ after James 
Watt. It is an interesting; fact that James 
Watt introduced the term horse-power in 
connection with his early steam engine, 
and, in accordance with international 
usage, of naming practical units after the 
names of distinguished scientists, Watt's 
name has been selected in connection with 
the international unit of activity. An 
activity of 1 foot-pound per second is 
an activity of 1.355 joules-per-second or 
1.355 watts. Similarly, an activity of 1 
horse-power, or 550 foot-pounds-per-sec 



24 ELECTRIC STREET RAILWAYS. 

ond, is an activity of 550 X 1.355 = 746 
Joules-per-seconcl, or 746 watts. If we 
multiply tlie number of horse-power 
whicli are being developed in any macliine 
by 746^ we obtain tlie activity of that 
machine expressed in watts. As the rate 
of 0.738 foot-pound -per-second is a very 
small nnit, being about 26 per cent, smaller 
than the foot-pound per second, and 
requiring, therefore, large numbers to 
express large powers, in dealing with 
engines, it is customary to nse a deci- 
mal multiple of this unit, so that the 
practical international itnit of activity 
is the Jcilowatt^ or 1,000 watts. Conse- 
quently, the horse-power, being as above 

746 
mentioned 746 watts, is /TTTT^ths of the 

i,OOU 

larger unit, or the kilowatt, and may be 
taken as, approximately, 3/4ths of a kilo- 
watt. A kilowatt will, therefore, be 4/3rds 



ELEMENTARY ELECTRIC PRINCIPLES. 25 

or 1 l/3rd horse-power, approximately. 
When we speak of a dynamo or motor 
as having a capacity of 100 kilowatts, (that 
is to say of being capable of maintaining 
an activity of 100 kilowatts, or 100,000 
watts = 100,000 Joules-per-second = 73,800 
foot-pounds-per-second,) we mean an 
activity of 1 1/3 x 100 = 133 horse- 
power, approximately ; or, 134 horsepower 
more nearly. 

The problem which presents itself to 
the street railway manager is that of 
economically driving street cars by electric 
power, and it is to be carefully remem- 
bered that the same amount of power 
must be exerted by the engines in the 
power house as by horses draAving the 
cars along the streets at the same rate. In 
fact the engines in the power house will 
have to work harder, or develop a greater 



26 ELECTRIC STREET RAILWAYS. 

activity tlian the horses, owing to the 
necessary losses of power which inci- 
dentally occur in transmission. If, for 
example, we imagine that all the cars in 
the streets of the city are travelling steadily 
along at the same average rate as the pis- 
tons of the engines in the power house, then 
the pull exerted by the pistons will be 
equal to the aggregate equivalent pull of 
all the cars, increased by a certain amount 
corresponding to losses in transmission. 

It remains now to show how power can 
be calculated and expressed in electric 
units. In other words, if we require to 
supply a certain activity in horse-power or 
kilowatts to a moving car, we need to find 
how to express this power in relation to 
electric circuits, since the power must be 
conveyed by the electric circuits from the 
power house to the car. We will, there- 



ELEMENTARY ELECTRIC PRINCIPLES. 27 

fore, discuss the elementary principles of 
electric circuits. 

An electric circuit is a conducting path 
provided for the passage of electricity. It 
connects an electric source or generator, 
with the devices to be operated by the 
electric current. Such a circuit is said to 
be made or closed when its path is com- 
pleted, and is said to be hroTceii or opened 
when its path ts interrupted at some point 
or points. Thus, in the case of the elec- 
tric car, an electric circuit exists between 
the power house where the current is 
generated, through the trolley wire and 
track, to the motors of the car. When 
such a ch'cuit is closed, the current passes 
through the car, and drives the motor or 
motors. On the contrary, when the circuit 
is opened by the motorman at the switch, 
the current ceases to flow. 



28 ELECTRIC STREET RAILWAYS. 

Fig. 1, represents a simple electric cir- 
cuit consisting of a generator G^ a trolley 
wire W Wy a car with its trolley 
Ty motors m m^ and the track K K^ 
employed as a return conductor. What 
passes through this circuit is an electric 
floWy generally called an electric current. 

w > — V _W' 



^a 



Fig. 1. — Simple Car Circuit. 

In order to obtain definite ideas concern- 
ing an electric current, a unit of electric 
current^ or rate-of-flow, called an ciinperey is 
employed. It will be advisable, however, 
before discussing the value of the ampere, 
to consider certain other quantities which 
are always intimately connected with 
every electric circuit. Turning our atten- 



ELEMENTARY ELECTRIC PRINCIPLES. 29 

tion first to the generator G^ it is necessary 
to observe that the primary function of 
the generator is not, as is ordinarily 
believed, to produce electric current, but 
to produce in the circuit a variety of force, 
called electromotive force^ Avhicli is gener- 
ally abbreviated E. M. F. AVhen the 
generator is driven by an engine it will 
supply an E. M. F. whether the electric 
circuit is open or closed, that is to say, 
whether an electric current can or cannot 
flow in the circuit. In other words, the 
generator, when running, alwa3^s supplies 
E. M. F., but no current can be sent 
throuo:h the circuit until the circuit is 
closed. This corresponds to the case of a 
reservoir, which produces a water pressure 
whether the water be escaping under that 
pressure or not. 

In Fig. 2, a rotary pump P, is supposed 



30 



ELECTRIC STREET RAILWAYS. 



to be placed in a power house situated by 
the side of a river K K^ and provided with 
a pipe by which it can draw water from the 
river and send it through the pipe W W. 
M^ is a water motor situated at some con- 




w 






i 



"J 



Fig. 2. — Simple Watek Circuit. 



venient point and connected with the 
main pipe W W, by a small branch pij)e, 
in which is placed a valve V. When the 
valve is closed, the motor Ji^ is prevented 
from running, since no water current 
passes through it. The hydraulic circvit 
W W^ K K^ may then be said to be hrohen 



ELEMENTARY ELECTRIC PRINCIPLES. 31 

or open. When, however, the valve FJ is 
opened, Avater passes through the motor 
J/J and discharges into the river, thus clos- 
ing the hydraulic circuit, and permitting a 
water current to flow through the circuit. 
It is evident that whether the valve FJ be 
opened or not, the generator or water 
pump P^ will develop, when running, a 
pressure or vjatermotive force in the pipe 
W Wj but that no current or flow of water 
can take place until the valve F, permits 
it to do so, thus closing the circuit. Here 
the loatennotive force^ produced by the 
action of the pump whether the hydraulic 
circuit be opened or closed, corresponds to 
the electromotive force produced by the 
generator whether the electric circuit be 
opened or closed. 

The pressure generated in the supply 
pipe W Wy by the pump P, might be 



32 ELECTKIC STREET RAILWAYS. 

expressed in pounds-per-square-inch ; or, as 
the pressure produced by a column of 
water a certain number of feet in height. 
In the electric circuit the pressure pro- 
duced by the action of the generator G^ is 
expressed in units of electromotive force^ 
called volts. In street-car systems the elec- 
tric pressure produced by the generator is 
almost invariably about 500 volts ; that is 
to say, the pressure between the trolley 
wires and the track is maintained, approxi- 
mately, at 500 volts, while the pressure at 
the power house between the terminals of 
the generator G^ may be somewhat in 
excess of this, say 550 volts, in order to 
make up for the loss of pressure occurring 
in the circuit. 

If a reservoir i?, Fig. 3, filled with water 
and maintained at a constant level L X, be 
allowed to discharge steadily through two 



ELEMENTARY ELECTRIC PRINCIPLES. 33 

pipes, as indicated in Fig. 3, one pipe A B^ 
being a long, narrow pipe, and the other 
C D^ being a short, wide l)ipe, it is evident 
that a much greater flow of water will 
take place in a given time through the 
pipe G D^ than through the pipe A B^ 
since the water pressure at the openings A 



Vr-^ 



Fig. 3. — Resistance of Watek Pipes. 

and C^ is the same ; namely, the height of 
water in the reservoir. The difference in 
the rate-of-flow of water may be ascribed 
to the different resistance offered by the 
two pipes to the flow of water, the resist- 
ance of the long, narrow pipe being com- 
paratively great, and that of the short, 
wide pipe being comparatively small. 



34 



ELECTEIC STREET RAILWAYS. 



In the same way, Fig. 4, represents an 
electric generator G^ which, when running, 
acts the part of the reservoir in the pre- 
ceding case, since it supplies a steady elec- 
tric pressure between its terminals. If 
two circuits are closed to this pressure, one 
through a long, thin wire A A! B' B^ and 




Fig. 4. — Resistance of Conducting Wires. 

the other, through a short, thick wire C O 
D' Dj then the electric flow or current, 
which will pass through these two circuits, 
will be very different, a comparatively 
small or feeble current passing through 
the long, fine- wire circuit, and a compara- 
tively strong, or heavy current, passing 
through the short thick-wire circuit. 



ELEMENTARY ELECTRIC PRIIS^CIPLES. 35 

Tills difference in flow or current be- 
tween the two circuits may be .ascribed to 
a difference in Avhat is called their electric 
resistance. The electric resistance of a 
long, thin-wire circuit is comparatively 
great ; i, e,^ it offers a comparatively great 
obstacle to the passage of electricity under 
the pressure of the generator G y while a 
short, thick-wire circuit has a compara- 
tively small electric resistance; i. e.^ it 
offers a lesser obstacle to the passage of 
electricity. 

Electric resistance is usually measured 
in terms of a iinit of resistance called the 
olim^ after Dr. Ohm of Berlin, who fii'st 
pointed out the laws regulating the flo\V' 
of electricity in conducting circuits. The 
amount of resistance ; i. e,j the number of 
ohms in a given uniform conductor, such as 
a copper wire, depends upon the length of 



36 ELECTRIC STREET RAILWAYS. 

the wire, upon its area of cross-section and 
upon its physical condition. The longer 
and narrower a wire, the greater will be 
its electric resistance. In the same way, 
the longer and narrower a pipe, the 
greater its water resistance; on the con- 
trary, the shorter a wire and the greater its 
area of cross-section, the smaller will be 
its resistance. An ordinary copper trolley 
wire, Avhich is No. 0, American Wire 
Gatige, with a diameter of 0.325", has a 
resistance per mile of, approximately, half 
an ohm, so that 2 miles of this wire 
would have a resistance of, approximately, 
1 ohm, and 1 foot of the wire would 

have a resistance of ^--— - x - = -tt^^tttt 

0,280 2 10,560 

ohm, approximately. If the trolley wire 
instead of being No. gauge were No. 
0000, which is a wire about twice as heavy 
as No. 0, having a diameter of 0.46'', it 



ELEMENTARY ELECTRIC PRINCIPLES. 37 

■ would have only half the resistance of No. 
0, and, therefore, approximately, l/4th ohm 
per mile. 

In Fig. 5, five copper wires, having dif- 
ferent lengths and areas of cross-sec- 



B lo c 



A lo c 



C lO c 
^ 20Z 



E 40i: 



Fig. 5. — Resistance of Wires. 

tion, are diagrammatically represented. 
Aj represents a trolley wire 1 mile long 
and 0.325'' in diameter, having, there- 
fore, a resistance of approximately 0.5 
ohm. Bj is a wire 2 miles long of the 



38 ELECTRIC STREET RAILWAYS. 

same cross-section, and, therefore, offer- 
ing 1.0 ohm. C^ is a wire half a mile 
long of the same cross-section, and, 
therefore, offering a resistance of, approxi 
mately, 0.25 ohm. J9, is a wire 1 mile 
long, but having a cross-section, as repre- 
sented on the left hand side, say twice that 
of any of the wires, A^ B^ or (7. It will, 
therefore, have half the resistance of \4, or 

5 

~^— — 0.25 ohm. E, is a wire 0.65" in 

2 ' 

diameter, having, therefore, four times the 
cross-section of A^ and being 2 miles in 
length. If the wire were of the same cross- 
section as A^ it would have 0.5 X 2 = 1 
ohm, but being four times as heavy, its 
resistance will be one-quarter of this, or 

~- — 0.25 ohm. Consequently, C^ Dj 

and E, have all the same resistance, 
although their dimensions are so different. 



ELEMENTAEY ELECTRIC PRINCIPLES. 39 

If, therefore, the cross-section and 
length of any copper wire be known, we 
can determine what its resistance will be, 
assuming that the conducting power of the 
substance of the wire is the same as that 
of the trolley wire we have selected as our 
standard. The resistance will be directly 
proportional to the length, and inversely 
proportional to the area of cross-section ; 
or, in other Avords, if the length be doubled 
the resistance will be doubled, while if 
the area of cross-section be doubled the 
resistance will be halved. 

We have hitherto considered copper 
wires only in estimating the resistance of 
a circuit. AVhen any other conducting 
material, such as iron, is employed, the 
resistance of a wire having a given length 
and cross-section will be materially dif- 
ferent. Thus, an iron wire has, approxi- 



40 ELECTRIC STREET RAILWAYS. 

mately, 6 1/2 times as miicli resistance as 
a wire of copper of equal dimensions. 
Iron trolley wires are, therefore, never 
used, for tlie reason that it would be nec- 
essary to employ a wire having about 6 1/2 
times the cross-section of ordinary trolley 
wire to liave the same conductance ; i. e.y 
ability to conduct electric current. Iron, 
however, enters into street railway circuits 
in the form of the tracks, Avhich, as we 
have seen, form a portion of the return 
circuit to the power liouse. 

The dimensions of a wire which has a 
resistance of 1 ohm will necessarily vary 
with the character of the material of which 
the wire is composed. Thus, in copper, its 
length might be approximately 2 miles, if 
its diameter Avas that of a trolley wire, 
0.325''; or, its length might be only 1 
foot, if of No. 40 American Wire Gauge, 



ELEMENTARY ELECTRIC PRINCIPLES. 41 

having a diameter of 0.003145" ; if of iron, 
a length of about 900 feet of trolley wire ; 
and, roughly, 2 inches of No. 40 wire 
would have a resistance of 1 ohm. In 
all cases the exact resistance Avould de- 
pend upon the degree of purity of the 
metal, as well as upon its physical condi- 
tion ; that is to say, upon its hardness, 
and temperature. Since mercury is a 
metal, which is fluid at ordinary tem- 
peratures, and can be readily obtained in a 
nearly homogeneous and pure condition, 
the ohm has been practically defined as 
the resistance of a column of mercury 
1.063 metres in length, and 1 square 
millimetre in cross-section, at the temper- 
ature of meltino; ice. 

It is evident from what we have said 
that the quantity of water which flows, in 
any given time, through the pipe referred 



42 ELECTEIC STREET RAILWAYS. 

to in connection with Fig. 3, will depend 
both on the pressure or head of water in 
the reservoir, as well as upon the resist- 
ance which the pipe offers to the flow. In 
the case of the electric circuit the same 
rule applies, that is to say, the quantity of 
electricity which passes or flows in an elec- 
ti'ic circuit, depends not only upon the 
electric pressure in the circuit which 
causes the flow, but also upon the resis- 
tance of the circuit which opposes it. 

In the case of the electric circuit the 
electric current is related to the E. M. F. 
and to the resistance in accordance with a 
law generally knoAvn as Ohm's laio. This 
law may be expressed as follows : 

The current strength in amperes flowing 
through a circuit, varies directly with the 
pressure or E. M. F., and inversely with 



ELEMENTARY ELECTRIC PRINCIPLES. 43 

the resistance; so that if we divide the 

number of volts in the E. M. F. by the 

number of ohms in the resistance, we obtain 

the current strength in amperes; or, con- 

. , volts 

cisely, amperes = —. . 

^^ ^ ohms 

Thus, if a circuit contains an E. M. F. of 
10 volts, and a resistance of 5 ohms, the 

current in the circuit would be -^ — 2 

5 

amperes. 

We have seen, in connection with Fig. 3, 
that the quantity of water which flows per 
second through the water pipe from the 
reservoir, depends both on the pressure at 
the reservoir, and on the resistance of the 
pipe. This, however, is only true when no 
obstacle to the flow of the water exists save 
the I'esistance of the pipe itself. If, for 
example, instead of permitting the water 



44 



ELECTRIC STREET RAILWAYS. 



to escape freely from the open end of the 
pipe it be first caused to pass through, and 
actuate, a water motor, then the condi- 
tions of flow will be profoundly modified, 
much less water flowing through the pipe 
in the second case than in the first. 



If, for 




-<?[" 
c* 






f 



i 



i 



H 



M 



^W^] 



Abcd'efelx 

Fig. 6. — Hydraulic Gradient. 



example, as in Fig. 6, the reservoir H, is 
capable of discharging by the pipe A k\ 
either through the faucet k\ into tlie air, 
or through the faucet I, after passing 
through the motor J^ the flow in the two 
cases will be very different. In the first 
case the pressure at the reservoir will be 
that due to the height of the water A A\ 
say 50 feet, while the pressure at the dis- 



ELEMENTARY ELECTRIC PRINCIPLES. 45 

charge point, will simply be tliat of the 
external air, or a column of feet. In 
other words in discharging through the 
pipe the water pressure suffers a drop as 
represented by the dotted line A' k\ and 
the pressure at the intermediate points is 
indicated by the points b\ c\ d\ e\ f\ g\ It. 
If, however, the faucet h'y be closed, and 
that at ?, be opened, thereby establishing 
communication tlirough the water motor 
J/J the motor will commence to operate, 
and in so doing will develop a hach pres- 
sure^ or counter toatermotive forces which 
opposes the flow of water and acts like a 
resistance. The pressure at h\ under these 
circumstances, instead of being feet, w^ill 
rise to F, and the drop of pressure, which 
has taken place in the tube A h'^ will have 
diminished from A A' to Ic X, with a cor- 
respondingly reduced flow of water through 
the pipe. 



46 



ELECTRIC STREET RAILWAYS. 



Similarly, if the electric circuit repre- 
sented in Fig. 2, be so modified as in Fig. 
7, that it may be closed either at c c, di- 
rectly back through the track, or at H^ 



a-^^=— 



— -ill' 




^ 



M 



: 



K K 

Fig. 7.— Electric Gradient. 

through an electric motor M, the electric 
flow or current in amperes will be very 
different in the two cases. If the circuit 
be closed through the track wire at c c, 
the pressure, at A, will be say 500 volts, 
as represented by the dotted line A a, and 
supposing the length A H, to be 1 mile 
of trolley wire, then neglecting, for con- 



ELEMENTARY ELECTRIC PRINCIPLES. 47 

venience, the resistance of the track and 
generator, the resistance of the circuit will 
be 0.5 ohm, and the current strength in 
the circuit 500 volts -f- 0.5 ohm = 1,000 
amperes. 

If, however, the circuit be closed through 
the motor M^ the latter will be actuated by 
the current and will be set into rotation, 
whereby a hack pressure^ ov counter electro- 
motive force^ usually abbreviated C. E. 
M. F., will be set up in the motoi*, 
of say, 450 volts, as represented by the 
dotted line H li ; so that the effective 
pressure or E. M. F. which drives the 
current through the circuit, will be re- 
duced to lih'^ 500 - 450 = 50 volts, 
and the current strength, neglecting the 
resistance of the generator motor and 
track, will be, 50 volts -^ 0.5 ohm = 100 
amperes. 



48 ELECTRIC STREET RAILWAYS. 

A flow of water is sometimes rated as 
being a certain quantity of water; i, e,j a 
certain number of cubic feet or gallons per 
second. In the same way the electric flow 
may be rated as being a certain quantity 
of electricity passing through the circuit 
per second. The unit of electric quantity 
is called the coulomb^ and has been so 
chosen that a flow of 1 coulomb per sec- 
ond is called an ampere. Consequently, a 
flow or current of 1 ampere, maintained in 
a circuit for 1 minute, represents a total 
flow of 60 coulombs of electricity, and, 
maintained for one hour, a total flow of 
3,600 coulombs. 

When an E. M. F. acts on a broken or 
open circuit, it is unable to send any 
current through the circuit, and will, 
therefore, do no work. Thus, when the 
generator at the power house is driven 



ELEMENTARY ELECTRIC PRINCIPLES. 49 

by an engine and supplies an E. M. F. 
of 500 volts to tlie trolley system con- 
nected witli it, no current will pass 
through the generator if there be no cars 
on the line, assuming that the wires are 
properly insulated. Under these circum- 
stances the generator will not be supply- 
ing any power, and the engine will have 
no work to do except to drive the genera- 
tor against its friction. In fact, except 
that the generator armature is magnetized, 
it behaves like a mere wheel of copper 
and iron, so supported on an axis in bear- 
ings, that it might be rotated with a very 
small expenditure of power. When, how- 
ever, the circuit of the generator is closed 
by the connection of the cars with the 
trolley wire, so that a current is trans- 
mitted throuo;h the circuit or circuits 
under the pressure of 500 volts, the 
generator does work at a rate which ^vill 



50 ELECTRIC STREET RAILWAYS. 

depend upon the amount of current sup- 
plied^ the greater the current strength in 
amperes delivered to the trolley system, 
and distributed to the cars^ the greater 
will be the activity which the generator 
has to supply, and the greater will be the 
activity which the engine must supply to 
drive it, so that when the load comes on 
the system by the operation of the cars, 
the generator which previously reqnired 
say 20 horse-power only to revolve it, 
may now require the engine to supply 500 
horse-power, which activity will be trans- 
formed into electric activity in the circuit. 
If we multiply the pressure in volts by 
the current strength in amperes Avhich is 
being supplied by that pressure, we obtain 
the activity supplied in watts. Thus, if 
a generator supplying 550 volts at its 
terminals to a trolley system delivers a 
current strength of 50 amperes through 



ELEMENTARY ELECTRIC PRINCIPLES. 51 

the circuit containing its armature, trollc)', 
street-car motor, and track, then the ac- 
tivity supplied by the generator at its ter- 
minals will be 550 volts X 50 auiperes = 
27,500 watts = 27.5 kilowatts (usually ab- 
breviated KW) = 36.85 HP = 27,500 
joules-per-second = 20,268 foot-pounds-per- 
second. The engine would have to supply 
more poAver than this to the genei'a- 
tor, since it would have to make up 
for the loss of power in the generator 
owino:: to its mechanical and electrical fric- 
tions, but if the generator had an efficiency 
of 90 per cent., that is to say, if its output 
was 90 per cent, of its intake, then the 
activity which the engine would have 
to supply to the generator would be 

27,500X100 ^^^^. ^^ ^^^„ 

— ^ — — = 30,555 watts = 30.55o 

KW - 40.94 HP = 30,555 jcniles-per- 
second = 22,517 foot-pouncls-per-second. 



52 ELECTRIC STREET RAILWAYS. 

Just as the total amount of work ex- 
pended by water escaping from a reser- 
voir, is equal, in foot-pounds, to the 
number of pounds of water multiplied by 
the number of feet through which it falls, 
so the total amount of work expended by 
electricity in flowing through a conductor 
or circuit is equal, in joules, to the number 
of coulombs of electricity multiplied by 
the number of volts difference of electric 
level, or pressure, under which it passes. 
Thus a current of 50 amperes flowing 
under a pressure of 650 volts, represents a 
flow of 50 coulombs-per-second under that 
pressure and an amount of work equal to 
50 X 550 = 27,500 joules in each second, 
or, in one hour of 3,600 seconds, a total 
work of 3,600 X 27,500 = 99,000,000 
joules. But Ave have seen that the ac- 
tivity in this circuit is 27,500 watts, and 
this activity maintained for an hour will 



ELEMENTARY ELECTRIC PRINCIPLES. 53 

require an expenditure of 27,500 watt- 
hours, or 27.5 kilowatt-hours. A tvatU 
liour is, therefore, a quantity of work equal 
to 3,600 joules, or 2,657 foot-pounds, wliile 
a hihwatt-hour^ the unit of a\ ork usually 
employed Avith large electric machines, will 
be 1,000 times as much, or 3,600,000 
joules = 2,657,000 foot-pounds. 

If a pressure of 550 volts is maintained 
steadily at the generator terminals, under 
all conditions of load, the pressure at the 
trolley of the single car we have con- 
sidered, will be less than 500 volts by an 
amount which will depend npon the size 
and number of the conductors in the net- 
work supplying it, and upon the length of 
those conductors, or the distance of the 
car from the power house. Thus, if the 
car be 1 mile from the power house, and 
if the track have, for simplicity, a negligi- 



54 ELECTRIC STREET RAILWAYS. 

ble resistance, while tlie single trolley wire 
supplying tlie car has a resistance of 0.5 
ohm per mile, then the resistance between 
the generator and the car will be 0.5 
ohm, and the drop in this length of con- 
ductor will be 50 amperes X 0.5 ohm = 
25 volts, so that the pressure at the termi- 
nals of the car motor as determined by 
a voltmeter y or instrument for measuring 
the number of volts, would be 550 — 25 = 
525 volts, and when the car was operating, 
the voltmeter, if connected between the 
trolley wire and the track at the car, 
would show this pressure, while as soon as 
the car was disconnected by opening the 
switch, the pressure between the trolley 
wire and the track would immediately 
rise to 550 volts, assuming no other car or 
leakage current to exist over the system. 
The amount of drop which will be pro- 
duced over a given length of conductor 



I 



ELEMENTARY ELECTRIC PRINCIPLES. 55 

will depend entirely upon the current 
strength, so that if we double the current 
strength we double the drop. 

The activity which the motor will 
receive at its terminals will be the current 
strength in amperes, (which is the same 
all through the circuit when only one car 
is employed,) multiplied by the pressure at 
its terminals. Thus, in the preceding case, 
the pressure being 525 volts at the motor 
terminals between trolley and track, wliile 
the current strength is 50 amperes^ the 
activity absorbed by the motor will be 
525 volts X 50 amperes == 26.25 KW, or 
1.25 KW less than that supplied by the 
generator to the line. This activity of 
1.25 KW is expended in the line as heat, 
uniformly distributed through its sub- 
stance ; for, the drop being 25 volts, and 
the current strength 50 amperes, the activ- 



56 ELECTRIC STREET RAILWAYS. 

ity expended in this conductor will be 25 
volts X 50 amperes = 1,250 watts, — 1.25 
KW expended entirely as heat. 

Of the 26.25 KW delivered to the 
motor, only a certain fraction will be use- 
fully employed in driving the car, the 
remainder being uselessly expended in 
heating the motor. If the efficiency of 
the motor be 80 per cent., then the activity 
usefully expended in the preceding case 

80 
will be 26.25 x ^^ = 21 KW = 28.14 

HP = 21,000 joules-per-second = 15,480 
foot-pounds-per-second. This activity will 
be supplied to the shaft of the motor. 
Assuming at present that no power is 
wasted in gears, then this activity will be 
available for propelling the car. For 
example, if the car friction were very 
small, and its total weight, including 



ELEMENTARY ELECTRIC PRIKCIPLES. 57 

passengers was 30,000 pounds, then the 
activity supplied would be ca]3able of lift- 
ing 30,000 pounds through a distance of 

15,480 

o^ .w^.. = 0.516 foot-per-second. With a 

1 per cent, grade this would represent a 
speed of 51.6 feet-per-second, or 35.2 miles- 
per-hour, and with a 10 per cent, grade 
it would represent a speed of 5.16 feet 
per second, or 3.52 miles-per-hour. 

It is evident, therefore, that the activity 
which can be communicated to a moving 
car for a given activity supplied at the 
driving shaft of the engines, depends upon 
the efficiency of the generator, the effi- 
ciency of the motor, and the efficiency of 
the line conductor, including under this 
term, the track. 

The efficiency of a motor or generator is 



58 ELECTRIC STREET RAILWAYS. 

the ratio of the output to the intake. The 
efficiency of a line conductor or circuit 
may also be regarded as the ratio of the 
output to the intake, the intake being 
measured at the generator terminals and 
the output at the motor terminals. The 
efficiency of a generator or a motor usually 
increases with the load up to full load or 
nearly full load, so that, under ordinary 
circumstances the more work we can get 
the motor or generator to do, within the 
limits of its capacity, the greater the propor- 
tion of useful work delivered, to the work 
received, although the loss of work will 
be absolutely greater. Thus, a street car 
motor, whose maximum activity is rated 
at 15 KW (approximately 20 HP) would 
require, perhaps, 2 KW to run it when 
entirely free from all load or disconnected 
from its gears ; i. ^., when doing no use- 
ful work^ so that its efficiency would be 



ELEMENTARY ELECTKIO PRINCIPLES. 59 


^ = 0. When fully loaded, however, it 

might waste 3 KW and deliver 15 KW, 

so that its intake would be 18 KW, and 

15 
its efficiency j^ =0.833 = 8 3. 3 per cent. 

Its efficiency may, therefore, increase from 
to 83.3 per cent, from no load to full 
load, although the actual loss of activity 
in it would increase in the same range 
from 2 KW to 3 KW. The same princi- 
ples apply to a generator, and for this 
reason it is always more economical to 
operate generators at a fair proportion of 
their full load. 

In the case of the line conductor or con- 
ductors, including track conductoi's, the 
case is different. The efficiency is always 
less as the load increases. Thus, if we 
supply a current strength of 1 ampei^e 
over a. circuit of troUev conductor and 



60 ELECTRIC STREET RAILWAYS. 

track, having a total resistance of 1 ohm, 
then the drop in this circuit will be 
1 ampere X 1 ohm — 1 volt, and if the 
pressure at the motor be kept at 500 volts, 
the pressure at the generator will have to 
be adjusted to 501 volts ; or, if the pressure 
at the generator be kept at 500 volts, the 
pressure at the motor terminals will, with 
a current of 1 ampere, automatically be- 
come 499 volts. If, however, 2 amperes 
be supplied through the same circuit, 
the drop will double, or will become 2 
volts, and the pressui'e at the generator 
will be 502 volts, if that at the motor is 
500. In the former case the efficiency of 

... . . .... 500 ., , 

the line circuit will be ^ttt ; m the latter 

501 ^ 

case it will be . Similarly, if the cur- 

502 *^' 

rent strength be increased to 100 amperes, 
the drop will increase to 100 volts, and 



ELEMENTARY ELECTRIC PRINCIPLES. 61 

^v itli 500 volts at the generator there will 

be 400 volts left at the motor, making the 

.. .400 
emciency ^^-r- = 0.8 = 80 per cent. It is 

evident, therefore, that the efficiency of the 
line continuously decreases with the load. 

It is clear from the preceding that if 
a trolley wire were very long, say 15 
miles, so that its resistance was 7.5 ohms, 
then the current strength of 50 amperes 
passing through the circuit to operate the 
car motor at the extreme distance from 
the power house would produce a drop of 
50 amperes X 7.5 ohms = 375 volts, leaving 
only 175 volts pressure at the motor when 
550 volts was the pressure at the generator 
terminals,^ and assuming no resistance in 
the ground-return circuit. The activity 
delivered by the generator would be 550 
volts X 50 amperes = 37.5 KW. The 



62 ELECTRIC STREET RAILWAYS. 

activity available at the motor terminals 

w^ould only be 175 volts X 50 amperes = 

8.75 KWj so that the efficiency of the line 

n . 8.75 
v^ould only be ^^ = 0.319 = 31.9 per 

cent.j v^hile the available speed of the car 
would be correspondingly reduced. In 
other words, owing to the great length of 
conductor, and resistance in the circuit, a 
large percentage of the activity would be 
expended in heating a long length of wire, 
instead of driving the car. 

The same condition of line efficiency 
would be produced by a number of cars 
over a shorter length of circuit. Thus, 
reverting to the case of a single mile of 
trolley wire, if a bunch of five trolley cars 
should start too;ether from the distant end 
of the line towards the power house, each 
taking 50 amperes of current strength, the 



ELEMENTARY ELECTRIC PRINCIPLES. 63 

total cuiTent strength supplied to tlie 
bunch would be 250 amperes, and the 
drop in the line would be 250 amperes 
X 0.5 ohm = 125 volts, making the pres- 
sure at the bunch 425 volts. The line 
efficiency, under these conditions would 

425 

be ,— - = 0.772 = 77.2 per cent. Conse- 
o50 ^ 

sequently, when the distance to which cars 
have to be run is great, or, when the 
number of cars and the current strength 
to be collectively supplied are great, the 
amount of copper employed to supply the 
system must be increased so as to reduce 
the effective conductor resistance. If, for 
example, we double the area of cross-sec- 
tion of the trolley wire, and, therefore, its 
weight per mile, we halve the resistance of 
the conductor per mile and, consequently, 
halve the drop, excluding track resistance, 
and, therefore halve the drop which will 



64 ELECTRIC STREET RAILWAYS. 

occur at any given clistance with any given 
load. 

There is, however, an obvious limit to 
the size of trolley wire which can be prac- 
tically employed. In fact, trolley wires 
are almost always constructed of No. 0, 
A. W. G. They are supplemented, how- 
ever, in practice, by what are called 
feeders J i. e.j feeding conductors which 
are separate from the trolley wares, but 
which lead from the generator in the 
power house and connect with the trolley 
wire at suitable distances along the track. 
Thus in Fig. 8, G^ is the generator, and 
C\ a car at a certain distance along the 
track. G F,, G F,, G F^, G F,, four 
separate feeders connecting with the trolley 
wire at different distances. As shown in 
the diagram, the current strength requii'ed 
to supply the car, is probably supplied 



ELEMENTARY ELECTRIC PRINCIPLES. 



65 



in a large measure by feeder G F^^ so that 
the feeders G i^, G-F^j and G i^, are 
comparatively idle. Consequently, the drop 
of the feeder G F^^ will be comparatively 




Fig. 8. — Feeder System. 



great with reference to that of the other 
feeders. F^^ F^^ F^^ and i^, are called feed- 
ing points. 



In practice it is usual to so arrange the 
feeders and the distances between feeding 
points, that when all the cars are being 



66 ELECTRIC STREET RAILWAYS. 

operated at average distances, the drop 
shall nowhere be in excess of 50 volts, and, 
therefore, that with 550 volts at the gene- 
rator terminals the pressure shall not be 
lower than 500 volts at any point on the 
line. 



CHAPTER IV. 

THE MOTOR. 

As is well known, the power whicli pro- 
pels a trolley car is obtained from the 
electric current transmitted tlirongli the 
circuit, by the intervention of an electric 
motor or motors, there being usually two 
motors placed on the truck of an ordinary 
street car. Fig. 9, shows the general con- 
struction of a truck Avith two motors M^ 
M^ in place, one geared to the axle of each 
pair of wheels. Reserving for description 
in Chapter V. the different methods 
adopted for the mounting or hanging of 
a motor, as well as the details in the 
construction of the car truck, we will now 

67 



68 



ELECTRIC STREET EAILWAYS. 



proceed to the general description of the 
motoi', its construction and operation. 



Fig;;. 10 shows a form of electric motor 
in extended use. Here the motor is com- 




FiG. 9. — Car Truck with Motors in Place. 

pletely enclosed in a cast-steel frame i^, 7^, 
^^ made in two halves, fitted together, as 
shown. Since the motor runs within a few 
inches of the surface of the street, and is, 
therefo]*e, exposed to dust, mud and Avater, 
it becomes absolutely necessary not only to 
provide it with a casing, but also to make 
this casing practically air and water tight. 
The main shaft of the motor is seen pro- 



THE MOTOR. 



69 



jectiiig throiigli its bearing at Ay and this 
bearing is lubricated by the grease box 0. 




Fig. 10. — Form of Electric Motor. 

The armature shaft is connected with the 
axle of the wheels on which the truck 
rests, by gear toheels enclosed in the gear 
cover Gj G, The gears are inserted in 



70 ELECTEIC STREET RAILWAYS. 

order to reduce the speed of tlie car as 
well as to increase the effective pull of 
the motor, as will be more clearly pointed 
out subsequently. The main axle passes 
through the bearing B^ lubricated by the 
grease box C. The motor is supported 
on the truck by the lugs Z! ^ L'. Access 
to the working parts of the motor is had 
by the lid L^ X, X, while a more nearly 
complete inspection can be obtained by 
unscrewing two bolts, one of which is seen 
at B^ and throwing back the upper half of 
the motor upon hinges H, H, The insu- 
lated cables K^ K^ pass through holes in 
the castings and supply electric current to 
the motor. This particular motor is called 
a G. E. 800 motor, the number 800 repre- 
senting that it is capable of exerting on 
the car a push of 800 lbs. weight at the 
main axle, when supplied with the full cur- 
rent strength, and mounted on 33" wheels 



THE MOTOR. 71 

on level rails. Two such motors when sup- 
plied with, full current strength, therefore, 
give a push of 1,600 lbs. weight to a car. 

Fig. 11, shows the same motor with the 
npper half thrown back on its hinges, thus 
permitting an inspection of the parts of 
the motor. Here, as in all this class of 
electric motors, the essential parts consist 
of an armature or rotating part A A^ with 
a commutator at M J/, upon which rest 
the brushes O^ C^ which carry the current 
from the trolley line into and out of the 
armature. The armature rotates between 
four poles, of which one is shown in the 
upper lid at jP, surrounded by a magnetiz- 
ing coil of wire W, The armature shaft 
has a pinion ^ secured to one of its ex- 
tremities, which engages with a gear-wheel 
on the main axle of the truck, w^hich axle 
passes through the bearings B, B. 



72 ELECTRIC STREET RAILWAYS. 

The armature of one of the electric 
motors above described consists essentially 
of three parts; namely, the armature 




Fig. 11.— Motor op Fig. 10 Opened. 

core, mounted on its shaft, the armature 
windings or coih, which are placed on 
the armature, and the commutator. The 



THE MOTOK. 



73 



general appearance presented by an arma- 
ture core, mounted on its shaft, is shown 
in Fig. 12. Here, as will be seen from an 







■.^^... ■ 






i 


t^S^'^^ 


^S^Hf^^^' • ' %. 




4y 





Fig. 12. — Unwound Armature. 



inspection of the figure, the core consists 
of a cylindrical body made of soft iron, 
If the armature core be made from a 



74 ELECTRIC STREET RAILWAYS. 

solid mass of iron, it has been found by ex- 
perience that during the changes in mag- 
netization to which it is subjected, when it 
rotates, deleterious electric currents called 
eddy currents, are generated in it. These 
currents cannot be employed in the ex- 
ternal circuit ; they merely serve to heat 
the armature core and so prevent the effi- 
cient operation of the motor. By adopt- 
ing the simple expedient of laminating the 
core ; that is, of forming it of thin sheets 
of iron, laid side by side, this difficulty is 
avoided. The armature core shown in 
Fig. 12, is laminated, that is, formed of 
discs or rings clamped together and sup- 
ported at right angles to the axis of the 
shaft. The edges of the cylindrical iron 
core thus formed are provided, circum- 
ferential] y, with a series of longitudhial 
grooves or recesses, as shown. These are 
intended for the reception of the insulated 



THE MOTOR. 75 

copper conductors that cany the electric 
current. 

In placing the insulated copper wire on 
the armature core, care is necessary to ob- 
tain a symmetrical disposition of the wires. 
One method of arrano-ino; the conductois 
on the core is shown in Fig. 13, which 
represents an armature in the process of 
windhio;. Armatures for motors are made 
in a variety of forms of which, perhaps, 
the vlRg armature and the cylinder arma- 
ture are the commonest. The armature 
shown in Fig. 13 is of the cylinder type. 
Here the wire is wound only on the out- 
side of the core. A sing;le cotton-covered 
^vire, starting at say A^ passes to B^ through 
the grooves, provided on the surface of 
the core for its reception. It then de- 
scends to (7, in the curved path shown, 
turns inwards and passes on to D^ when it 



76 



ELECTRIC STREET RAILWAYS. 



again crosses through the groove to E^ and 
so on. All the wires which are left pro- 
jecting on the left-hand side are intended 




Fig. 13. — Armature in Process of Winding. 

to be connected to the part called the com- 
mutator, the object of which will be ex- 
plained subsequently. 

A particular form of commutator is 
shown in Fig. 14. It consists, as shown, 



THE MOTOR. 



77 



of a number of segments of copper placed 
longitudinally on the surface of a cylinder, 
each strip being insulated from the adja- 




FiG. 14. — Form of Commutator. 

cent strips by means of a thin plate of 
mica. The commutator strips^ segments^ or 
hars^ as they are called, are connected to 
the free ends of the wires which are 



78 



ELECTRIC STREET RAILWAYS. 



soldered into the clips left for them. Fig. 
15, shows a completed armature, or the 
appearance of the armature in Figs. 12 and 



^ 


•A -x-?,-"^. 




^^^^^^~^ 


h 




^^^^^^^^^^.i 


.-, 




P ~ 



Fig. 15. — Wound Armature. 

13, when the process of connecting and 
soldering is complete. 

It now remains to explain the manner in 
which the electric current passing through 
the armature causes it to rotate. When 



THE MOTOR. 79 

the current enters the armature conductors 
at one brush and circulates around the 
coils of wire ^vrapped on its surface, it 
also passes through the coils of wire 
around the field magnets. By these means 
both the armature and the field poles are 
rendered magnetic, and it is to the mag- 
netic attractions and repulsions that take 
place between the movable armature and 
the fixed field poles, that the rotation of 
the armature ^nd the mechanical force it 
develops are due. Since, however, the 
form of electric motor employed in the 
street car is very compact and difficult to 
understand, it will be preferable first to 
consider a few simpler types of electric 
motors. 

It is a well known fact that when two 
magnets are brought near together, their 
unlike poles ; i. e.^ the north pole of one 



80 



ELECTRIC STREET RAILWAYS. 



and the south pole of the other, will 
attract, while their like poles will repel, 
so that if one of the magnets be free to 
move, it will come to rest in such a posi- 




Fig. 16. — Action Between Magnet and Active Coil. 

tion that opposite poles are adjacent. A 
conductor carrying an electric current^ 
acts like a magnet, so that if a magnet be 
approached to an active coil of conductor ; 
i. 6,j a coil carrying a current, as shown in 
Fig. 16, an attraction will take place be- 
tween the unlike pole of the magnet and 
the active coil. In the case of the coil of 



THE MOTOR. 81 

insulated wire, shown in Fig. 16, the faces 
of the coil become magnetic, as marted at 
S and A^. If the direction of the current 
through the coil be reversed, the polarity 
of the coil wall be reversed, so that, if the 
coil Avere free to move, it would turn 
around and present its opposite end to the 
magnet ; or, if prevented from doing this, 
would be repelled bodily by the magnet. 

If now the coil, instead of being sus- 
pended by the two wires Avhich carry 
the current into and out of it, is placed 
as shown in Fig. 17, that is, suspended 
flat and horizontally in the position 
a h c dy hj the two wires before the 
north pole iV, of the bar magnet, then, as 
soon as a sufficiently powerful current is 
passed through the coil, it will set itself at 
right angles to the magnet into the posi- 
tion a y G d\ as shown by the dotted 



82 



ELECTRIC STREET RAILWAYS. 



lines. If the current through the coil be 
reversed, the coil will turn around and 
present its opposite face to the magnet. 
This action can be intensified by employ- 




FiG. 17. — Deflection of Active Coil by Magnet. 



ing two bar magnets with opposite poles 
at iV^and S, as shown in Fig. 18 ; for, each 
magnet attracts the opposite face of tlie 
coil. By combining the two bar magnets 
into a single horseshoe magnet in the 
manner shown in Fig. 19, the action on 



THE MOTOR. 



83 



the coil can be rendered still more power- 
ful. 



In the simple form of apparatus shown 
in Figs. 17 to 19, the coil has been sup- 




Fig. 18. —Deflection of Active Coil by Opposite 
Poles of Two Magnets. 

ported in air. If, however, the coil be 
wound upon a cylinder of iron, as shown 
in Fig. 20, the magnetic power with which 
it tends to rotate is very much increased. 
Moreover, instead of employing ^perman- 
ent horseshoe magnet^ we may wind a coil 



84 



ELECmiC STREET EAILWAYS. 



of insulated wire C C\ around the soft iron 
Tiorseshoe magnet core^ shown in Fig. 20, 
and by passing an electric current through 
this wire we may obtain a more powerful 



/ 






\ 


r 






/ 




/ 






~TM~ 


V 



Fig. 19. — Deflection of Active Coil by Hoeseshoe 

Magnet. 



magnet than would be possible with any 
permanent magnet of steel. By this 
means we obtain a still more poAverful 
electronfiagnetic tivist or puUj technically 



THE MOTOR. 



85 



called the torque^ Avlien the current is 
allo\Yed to pass through the armature coil. 

It is evident that in the preceding cases 




Fig. 20. — Deflection of Active Coil Wound on Ikon 
Core by Electhomagnet. 



the motion of the coil will cease as soon as 
it sets itself at rio;ht ano;les to the line 
Joining the magnetic poles. If, however, 
the current in the coil could be automati- 



86 ELECTRIC STREET RAILWAYS. 

cally reversed; i. e,, changed in direction, 
as soon as tliis position was reached, the 
armature would turn round, or rotate, 
through half a revolution, when it would 
again come to rest at right angles to the 
line Joining the poles N^ S. The device, 
whereby the direction of the current 
through the coils is automatically reversed 
every time that the coil sets itself in the 
neutral or dead position, so as to ensure 
another half rotation, is called a coin- 
mutator^ because it commutes or changes 
the direction of current in the coils at the 
desired moment. 

Early forms of electric motors employed 
only a single coil on the armature, as 
represented in Fig. 20, but later forms 
invariably employ a number of coils dis- 
posed at uniform angular distances around 
the surface of the armature so as to main- 



THE MOTOR. 



87 



tain the twistiug power or torque uni- 
form in all positions. 

The continuous-current electric motor, 




Fig. 21.— Stationary Electric Motor. 



as in actual use on street cars, consists sub- 
stantially of a suitable combination of the 
parts just described ; namely^ of the arma- 



88 ELECTRIC STREET RAILWAYS. 

ture, of the field magnets and their poles, 
and of the commutator. A practical form 
of stationary electric motor is shown in 
Fig. 21, where JV and S, are the poles 
of a powerful electromagnet wound with 
many turns of insulated wire, and Ay 
the armature, which rotates between these 
poles. Cj is the commutator upon which 
the brushes ^, B, rest in such a manner 
that, by the rotation of the armature, the 
direction of current in the loops of wire is 
cliauged at the moment required to ensure 
a continuous rotation. 

Motors are made in a great variety of 
forms. For example, instead of having only 
two poles, four or more poles may be em- 
ployed. Thus Fig. 22, shows a form of 
four-pole or qnadripolar motoi\ with its 
four magnetizing coils N^ S>^ N^ S, pro- 
vided to produce the four poles. In this 



THE MOTOR. 



89 



particular case four sets of brushes B^ B^ 
are employed, of whicli only three are 
visible in the cut. The armature A, 




Fig. 22.— Stationary Quadripolar Motor. 



revolves in the space between the four 
poles, and the current is supplied to this 
armature from the brushes B^ B, through 



90 ELECTRIC STREET RAILWAYS. 

the commutator M. Here the field frame 
F F F,\^ of cast iron. 

Street-car motors are almost always of 
the quadripolar type. Owing to the fact 
that these motors have a very small space 
allotted them under the car, and are re- 
quired to be very light, the four magnet 
poles are as short as possible, and the field 
frame, instead of being made of cast iron, 
is of soft cast steel, which is much more 
advantageous from a magnetic point of 
view. In the motor of Fig. 11, there are 
four poles, two only of which, the upper 
and lower, are wound with coils of wire. 
The poles on the side being unwound or 
being, as they are sometimes called, conse- 
quent magnetic poles. Fig. 23, shows the 
castings for another form of quadripolar 
street-car motor. In this case, each of the 
four poles iV, 8^ N^ Sy is sun*ounded by a 



THE MOTOE. 



91 



magnetizing coil, and the whole field frame 
F F F^ is of cast steel. Id order to permit 
access to the intei*ior of the field frarae^ it 




Fig. 23. — Field-Frame Castings of Quadripolar 
Street-Car Motor. 



is made in halves and the upper is movable 
on a hinge P. The armature for this 
motor is shown in Fio;. 24 in three succes- 
sive conditions. At A, is seen the un- 



92 



ELECTRIC STREET RAILWAYS. 



wound core composed of sheets of iron 
punched with radial teeth, so as to form, 
when assembled, a compact cylinder with 
grooves or slots as shown. At B^ the 




Fig. 24. — Aumatuke for Motor of Field Frame in 
Fig. 23. 



insulated conductors have been placed in 
these grooves ready for connection to the 
commutator at the distant end of the core, 
while at (7, the finished armature is shown. 
The appearance of a similar motor, after 
being assembled, is shown in Fig. 25. 
Here A^ is the armature geared to the main 



THE MOTOR. 



93 



axle throiigli reducing gear, covered by the 
gear cover G G, B^ B^ are two brushes, 





Fig. 25. — Assembled Motor Open for Inspection. 



the armature winding being such that only 
two brushes need to be emploj^ed. This 
is the plan generally adopted with street 
car motors, while stationary qnadripolar 



94 



ELECTRIC STREET RAILWAYS. 



machines usually employ four brushes or 
sets of brushes, as shown in Fig. 22. ^y^y 
are the two poles in the upper half of the 
field frame, each being surrounded by a 







Mm 'mm 







^^P 
w 




Fig. 26. — Completed Street-Car Motor. 



magnetizing coil. The completed motor, 
closed and ready for suspension, is sho\vn 
in Fig. 26. Here J5, shows one set of 
brushes protected fi*om dust and mud by 
the shell S. F F, is the field frame, G G, 



THE MOTOE. 



95 



tlie gear cover. A, the armature shaft 
aud i?, the truck-wheel shaft. C] C, C\ 
the terminals of the motor from which 
wires lead to the controller or car switch. 




Fig. 27.— Brush Holder. 



A form of brush holder employed in the 
motor of Fig. 11, is shown in Fig. 27. 
This brush holder is of metal and is clamped 
in the slot C^ to its supporting frame 



96 ELECTRIC STREET RAILWAYS. 

througli which it receives the electric cur- 
rent. The brush slides freely in the guides 
G^ G. The brush being composed of a 
rectangular block of carbon, the arm A^ 
pivoted at P, maintains a uniform pressure 




Fig. 28.— Carbon Biujsh. 

at the back of the brush under the tension 
of the spiral spi'ing S^ thus pressing the 
brush against the surface of the commuta- 
tor beneath. The arm A^ can be with- 
drawn, and the brush lifted, by pulling 
with the finger upon the tongue D, A 
form of such brusli is shown in Fio;. 28. 



CHAPTER V, 

CAES Al^D CAR TRUCKS. 

A STREET car, as it appears ou tlie street, 
is composed of two distinct parts ; namely, 
the car hody^ or the enclosed space for the 
passengers, and the car truch^ or the part 
upon which the car body rests. Limiting 
our present consideration to the car truck, 
we find that this consists generally of a 
frame resting upon the axles of the wheels, 
through journal boxes. 

There are three methods of supporting 
car bodies on trucks ; viz., 

(1) By the use of a single rigid truck 
with four wheels and tw^o axles, the axles 

97 



98 ELECTRIC STREET RAILWAYS. 

remaining sensibly parallel in all positions 
of tlie car, whether on curves or on straight 
tracks. 

(2) By the use of two trucks, one at 
each end of the car. In this case the car is 
usually supported upon the swivel centre 
of each truck. 

(3) By the use of three trucks, the car 
being supported on the end trucks, and 
the centre truck being movable, so that the 
car axles are only parallel on straight 
tracks, and are radial on curves. 

A single truck is commonly used for 
short cars and the double or triple truck 
for long cars. 

Fig. 29, shows a particular form of 
single truck. F^ F^ F^ are solid forged 
side frames. B^ B^ are the journal boxes, 
in which the axles run, and on which the 



CARS AND CAR TRUCKS. 



99 



weight of the car rests, through the double 
spiral springs S, S. The car body is sup- 
ported on the steel beams £\ B\ which, in 
their turn, rest upon the side frames 
through the four spiral springs, and the 




Fig. 29. — Single Truck. 



two elliptical springs on each side. The 
wheels are provided with hrcike slioes Z, L. 



A form of truck for a doiihle-triick car 
is shown in Fig;. 30. Here the motor is 
mounted so as to drive the left-hand axle, 
and the weight of the car is so disposed 
upon the truck as to throw the principal 
share of the weight upon this pair of 

LOFa 



100 ELECTKIC STREET RAILWAYS. 

wheels in order to provide sufficient trac- 
tion and prevent the rotation of the motor 
from causing the wheels to slip. 

Fig. 31, shows another form of truck for 
a double-truck ca]' called a maximuifn trac- 




Fig. 30. — Truck of Double-Truce Car. 

tion truck. This truck has two axles, and 
two pairs of wheels of different diameters. 
The motor is suspended in sucli a mtmner 
as to drive the larger pair, nearly 9/lOths 
of the weight of the car being distributed 



CAKS AND CAR TRUCKS. 



101 



upon these wheels so as to obtain the 
maximum tractive effort. 

Fig. 32j shows a triple-tnich support^ 
called a Hohmson radial truck. Here the 




Fig. 31. — Maximum Traction Truck. 



car is supported upon the centres of the 
end trucks in such a manner that these 
may swivel freely, carrying the middle 
truck between them. Fio;. 33 illustrates 
the action of these trucks when going 
around a curve. It will be seen that the 
middle truck is pulled over to that side of 



102 



ELECTRIC STREET RAILWAYS. 



the car body which is on the outside of 
the curve. The advantage of double and 




Fig. 32.— Robinson Radial Truck. 

triple trucks is considerable with long cars, 
but for short cars they are usually con- 
sidered unnecessary, although they save 
some power and wear going around curves. 




Fig. 33. —Action of Radial Truck. 

The appearance presented by a single- 
truck car is illustrated in Fig. 34, which 



H-l 



I 

GO 



W 

d 
o 

W 

Q 




104 ELECTRIC STREET RAILWAYS. 

represents a car body 21 feet long and 28 
feet in length over all, with a width over 
wheels of 6 feet, a total width over all of 
7 1/2 feet, and capable of seating 30 
persons. The truck weighs without mo- 
tors 3,500 pounds, and the body 5,250 
pounds, making a total weight, without 
motors or passengers, of 8,750 pounds. 
Fig;. 35 shows a double-truck car. The 
car body is 25 feet long, and 33 feet over 
all. The width over wheels 6 feet, and 
over all 7 1/2 feet. Tliis car will seat 36 
persons. The weight of the truck with- 
out motor is 5,200 pounds, and the body 
5,850, making a total weight, without 
motors or passengers, 11,050 pounds. 

A form of journal hox is shown in Fig. 
36, Here the lid X, can be moved aside 
for examination, or for filling the box. The 
entire box is dust tight. The side frames 



106 ELECTRIC STREET RAILWAYS. 

are clamped to and riveted in the grooves 
B^ B^ so that the weight of these frames, 
and, therefore, the entire weight of the car 




Fig. 36.— Form of Journal Box and Support. 

pulls down upon the yoke A^ and presses 
the double spiral spring S^ upon the box 
L. The double spiral springs on all the 



OARS AND CAR TRUCKS. 



107 



boxes, therefore, bear the entire weight of 
the car. Fig. 37, shows a cross-section of 




Fig. 37.— Section of Box Shown in Fig. 36. 



these Journal boxes taken through the axis 
of the shaft. A, is the axis, £, B^ the 
brasses from which the ^veight is trans^ 



108 ELECTRIC STREET RAILWAYS. 

mitted to tlie axle, W, is the mass of lubri- 
cating material, jS, the double spiral spring 
supporting under compression the yoke Y. 
P^ is the spring packing faced with 
leather to keep out dust. J?, is a repair 
piece which is marked G, in Fig. 36. This 
repair piece, when removed by withdraw- 
ing two bolts, permits the frame to be 
lifted clear of the axles. 

Wheels for electric street cars are usu- 
ally 30 inches, 33 inches or 36 inches in 
diameter, and weigh from 300 to 400 
pounds each. The tread of the wheel ; 
i. ^., its running face, is usually chilled to 
a depth of 1/2 or 3/4 inch to improve its 
wearing qualities. A good wheel should 
run 30,000 miles. Wheels are usually 
forced upon their axles by hydraulic pres- 
sure, but in some cases they are bolted to 
collars on the axle, which collars are them- 



CAKS AND CAR TRUCKS. 



109 



selves forced hydraulically on the axle. 
There are two types of wheel, the open 
and the dosed. Fig. 38, shows a form of 




Fig. 38.— Open Car Wheels. 

open wheel and Fig. 39, a form of closed 
wheel. 



Motors may be mounted on the trucks 
in several ways. The most usual method 
is to support each motor partly on the 



110 



ELECTRIC STREET RAILWAYS. 



axle it drives^ and partly on a cross beam 
extending between the side frames. This 
is shown in Fig. 40, where the motor M^ of 







" 


31'- ■ ^ 'm9 


f^ 




'-.V.;.J!-.-";,^ 




-,i'rTr^.-«--<!tr.__-,___, — — — . 



Fig. 39.— Closed Car Wheel. 

the type shown in Fig. 11, is supported on 
the cross beam B B^ which is itself sup- 
ported from the side frames by the spiral 
springs 6', c^. These spiival springs are, of 
course, emplo3'ed to reduce the vibration, 
or jolting of the motor, wdien running over 
an uneven track. The cross beams, instead 



CAKS AISTD CAK TRUCKS. 



Ill 



of passing beneath the motor may pass 
above it, or on a level with its surface, as 
shown in Yig-. 41, where the beam £ JS. 





r/ |— .^ 








Fig. 40. —Method of Motor Suspension. 



rests above the spiral springs instead of 
beneath them. In Fio\ 42, another method 
is shown where the beams £ B, from w^hich 
the motor is suspended, are longitudinal 
and rest on spiral springs, which them- 
selves rest upon cross beams secured to 



112 ELECTRIC STREET RAILWAYS. 

the side frame of the truck. In this case 
very little of the motor's weight comes 
immediately upon the driving axle, almost 




Fig. 41. — Method of Motor Suspension. 



all beino; transmitted to the axle from the 



^ide fr 



side irames. 



A plan and side view of the ordinary 
motor suspension in a single-truck car are 
shown in Fig. 43, where tlie two motors 
M^ Afj are seen, each connected to one of 
the main axles through the gear G^ G. 
The motors are suspended partly upon the 
main axles and partly upon the cross 



CARS AND CAR TRUCKS. 



113 



beams B B^ and B Bj the four wheels 
W^ Wy W, W, are thus directly driven 
from the motor through the gears. 




Fig. 42.— Method of Suspending Motor. 



The gearing employed in connection 
with the electric street railway cars, is 
effected by means of a steel pinion upon 
the armature shaft, such as shown in 
Fig. 44. This pinion has 14 teeth, which 
are mechanically cut so as to mesh freely 



114 



ELECTRIC STREET RAILWAYS. 



into the teeth of the gear wheel fixed 
rigidly upon the car axle. This gear wheel 
is usually made of cast iron in two parts, 




Fig. 43.— Plan and Side Elevation of Motor 
Suspension. 



as shown in Fig. 45. The gear wheel 

shown has 67 teeth. The ratio of speed 

reduction between the motor and the car 

67 
axle is, therefore, in this case, j^ — 4.786. 

In other words, the car-wheel axle runs 



CARS AND CAR TRUCKS. 115 

4.786 times more slowly than the motor 
shaft. If we consider a car with 33 inch 
wheels, the circumference of the wheels 
will be 103.67 inches or 8.639 feet. This 
will be the distance through which the 
car will move for one complete revolution 




Fig. 44. — Armature Pinions. 

of the wheels. A speed of 1 mile per hour 
over the track, is a speed of 88 feet per 
minute, and, therefore, a rotatory speed of 
88 -^ 8.639 = 10.186 turns per minute of 
the car wheels. The speed of the motor 
armature will be 4.786 times this amount 
or 48.76 turns per minute. Consequently, 
for everj^ mile per hour that the car runs^ 



116 



ELECTRIC STREET RAILWAYS. 



the motors will make 48.76 revolutions 
per minute. Thus at 10 miles per hour 



vm®=MAi 




Fig. 45. — Axle Gears. 



they will each make 487.6 revolutions per 
minute. 



Pinions are sometimes constructed of 
hot pressed steel. Thus Fig. 46, shows a 



CARS AND CAR TRUCKS. 



117 



steel cyliuder before pressing and tlie com- 
pleted pinion wlieel pressed from such a 
cylinder. 




AFTER. 

Fig. 46.— Hot-Pressed Pinion, Before and After 
Pressing. 

The motors which we have hitherto 
considered are all single'V eduction motors^ 
that is to say, there is only one reduction 



118 



ELECTRIC STREET RAILWAYS. 



in speed effected by gearing between the 
motor axle and the car axle. During the 
early application of the street car motor it 
was very difficult to obtain good sloio-sj)eed 
motors of light weighty and^ consequently. 




Fig. 47. — Double-Reduction Motor. 

the expedient was adopted of reducing the 
speed down to that required for the car 
axle by a double reduction. Figs. 47 and 
48 show a type of doichle-redvction motor. 
In each figure^ Aj is the armature bearing 



CAKS AND CAR TRUCKS. 



119 



through which the axle passes. B^ is an 
intermediate shaft carryiDg a double-gear 
loJieel at one end as shown in Fig. 48, 
meshing with a double ])inio)i on the arma- 
ture shaft; while, at the other end, it 




Fig. 48. — Double-Reduction Motor. 



carries a pinion meshing into a gear wheel 
on the car-wheel shaft passing through 
the bearing C. In this type of machine 
the double reduction in speed varies from 
9 to 19, according to the size of the motor 
and requirements of speed and power. 
In recent times the double-reduction motor 



120 ELECTRIC STREET RAILWAYS. 

has almost disappeared. One difficulty 
with the double-reduction motor was the 
noise made by the rapidly running arma- 
ture pinion. To reduce this, rawliide 
pinions ; i. e.^ pinion wheels made up of 




Fig. 49. —Rawhide Pinion. 

discs of rawhide, cut into the proper 
shape, assembled and clamped together, 
were employed, of the type shown in Fig. 
49. The lifetime of such rawhide wheels 
was never very extended. 



CARS AND CAR TRUCKS. 

The life of steel and iron 



121 



gearing 

depends largely upon tlie care witli which 
the dust is excluded from them. In prac- 




FiG. 50.— Gear Cores. 



tice an increased life is ensured by enclosing 
the gear in a dust-proof gear cover, as 
shown in Fig. 50. 



122 ELECTRIC STREET RAILWAYS. 

It is evident that for safety of running 
cars through crowded thoroughfares, it is 
absolutely necessary to be able to stop a 
car with certainty in a short distance. In 
order to effect this, various forms of hrake 
mechanism are employed. These are either 
operated by hand, or by the electric current. 
Pneumatic car brakes have not come into 
any extended use up to the present time 
for this purpose, since they require the 
addition of a pneumatic compressor to the 
car equipment. 

A common form of lever hralce^ operated 
by hand, from either end of the car, is 
shown in Fig. 51 and also in Fig. 43. ^, 
JR\ are the projecting rods to one or other 
of which the power is applied by a chain 
and handle. Fig. 52 shows the ordinary 
hrake handle at the car platform. By 
rotating this handle the chain (7, is wound 



CARS AND CAR TRUCKS. 



123 



upon the handle shaft, thus hauling upon 
the brake rod B! . P^ is a pawl engaging 
with the pinion wheel on the brake handle 
shaft so as to hold or release the brake as 
desired. Fig. 51, shows that when one of 




Fig. 51.— Hand Brake Mechanism. 



the brake rods, say 7?, is pulled by the 
chain, the lever X, is dra^vn forward and 
by the action of the short bar Cj or brake 
beam clevis, the brake beam B is forced 
backwards, so as to cause the brake shoes 
H^ H^ to press against the treads of the 
wheel Wj W, At the same the brake 



124 



ELECTRIC STREET RAILWAYS. 



frame L R M H R L'^i^ forced forward, 
thus drawing the other brake beam B\ 
forward, and causing the shoes II\ H\ to 
bear against the tread of the wheels 




Fig. 52. —Brake Handle and Chain. 



W* W\ As soon as the tension is 
released from the brake rod, the brake 
frame L M M H H L\ releases and 
throws the shoes off the wheels. 



CARS AND CAK TRUCKS. 125 

When the arm is applied to the brake 
handle H^ Fig. 52, the pull so delivered is 
multiplied by the leverage of the handle 
over the chain. This ^^ull being delivered 
at R\ is again multiplied by the leverage 
of the brake lever Z. The combined 
leverag-e of the brake staff and brake lever 

o 

is usually about 50, so that a pull of 100 
pounds weight, delivered horizontally at 
the brake staff handle, represents a pull of 
about 5,000 pounds delivered at all four 
brake shoes, or about 1,250 pounds total 
pressure between each shoe and the wheel 
it grips. The effect of this pressure is to 
produce about l/8th of the pressure as a 
fj'ictional retarding force, so that if 1,250 
pounds pressure be supplied to each 
wheel, the retarding drag applied at the 
wdieel tread is. about 160 pounds. 

The turnbuckle T T^ enables the play 



126 



ELECTRIC STREET RAILWAYS. 



of the brake rods and brake arm to be ad- 
Justed so that any unnecessary delay in 
applying the brakes may be avoided. 

A form of electric car hrake, which 




Fig. 53. — Electric Brakes Mounted on Street Car 
Trucks. 

promises to come into extended use, is 
represented in Fig. 53. A truck is here 
represented with two motors M^ M^ in 
place, of the same character as shown in 
Fig. 11. In addition to the ordinary hand 
brake mechanism operating through the 



CARS AND CAR TRUCKS 127 

brake rods ;', 1% the brake levers l^ I 
the brake beam m^ and the shoes h^ h^ 
there is supplied an electric brake B^ on 
each car axle. This brake is in two 
parts ; namely, a cast iron disc (7, rigidly 
keyed to the car wheel axle, and, therefore, 
revolving with the car wheel, and a cir- 
cular shoe or compact electromagnet D^ 
facing Cj clamped to the motor and frame 
of the car, and, consequently, not rotating 
whether the car be runnino; or at rest. 
Wlien the car- is running there is no fric- 
tion between the shoe D^ and the disc C. 
As soon as it is desired to stop the car, 
the trolley circuit is first broken at the 
trolley switch by the motorman, thus cut- 
ting off the power from the line. As 
soon as this is done the motors which are 
still running by the momentum of the car, 
act as ordinary djmamos, and are capable 
of furnishing a temporary electric current 



128 ELECTIUC STREET RAILWAYS. 

as soon as a circuit is closed to their 
E. M. F. The coil of insulated wire in the 
interior of the magnet shoes D^ D^ of the 
brakes are placed in circuit with the motor 
armatures so as to receive this current. 

Under these circumstances a powerful 
electromagnetic attraction occurs between 
the shoes D^ D, and their iron discs C^ C^ 
tending to clutch them together and stop 
the wheels. The faster the car is running 
at the moment these brakes are applied, 
the more powerful is the current that is 
generated by the motors acting as dynamos, 
and^ consequently, the higher the brake 
action. 

There are two methods of controlling 
this brake, the first automatic, and the sec- 
ond under the control of the motorman. 
The braking po\ver, if uncontrolled, would 



CARS AND CAR TRUCKS. 129 

be so great that the wheels would be in- 
stantly locked and would skid or slide on 
the traclv. An automatic switch is placed in 
the circuit in such a manner that the cur- 
rent streno;th from the motors throus;h the 
brakes is limited to that w^hich will ^apply 
the maximum braking power without per- 
mitting skidding with a light car. More- 
over, the braking current passes through 
the controller to be subsequently described, 
and is thus regulated in strength by the 
motormaUj so that he can apply the elec- 
tric brake either suddenly^ or gradually, as 
he may desire. The advantao;e of the elec- 
trie car brake is the power it possesses, the 
swiftness with which it can be applied, and 
the fact that it is independent of all current 
taken from the trolley wire, since the 
moving motors supply the energy needed. 
The mechanism can, moreover, be attached 
to any car without great expense, while 



130 ELECTKIC STREET RAILWAYS. 

the ordiuary brake is left untouched for 
use in cases of emergency. A special ar- 
rangement is made to lubricate the rotating 
surfaces by means of a graphite brush car- 
ried in the shoes D^ D, This prevents ex- 
cessive wear and heating; for, in this brake, 
the retardation is very largely a magnetic 
pull rather than a mechanical friction, and, 
in this w^ay, effective brake action is 
secured without excessive rubbing. 

When the rails are slippery, by reason of 
a thin film of mud or frost, an application 
of the brake is apt to cause adhesion of the 
shoe to the brake wheel, and a skidding or 
slipping of the wheel on the track, instead 
of an adhesion between the wheel and the 
track and a slipping of the brake shoe on 
the wheel. The result of this skidding is 
to wear the tread of the wheel at the point 
of its periphery at which it slips along the 



CABS AND CAR TRUCKS. 131 

track, whereas in the normal application of 
the brake, this wear is uniformly distrib- 
uted over the entire wheel surface against 
the brake shoe. Under these conditions 
the Avheel tends to flatten at the point of 
skidding, and once a depression is formed, 
there is a continual tendency to increase 
the amount of flattening. Flat wheels are 
not only difiicult to brake properly, but 
produce an uneven jarring motion very dis- 
agreeable to tlie passengers. In order to 
increase the adhesion between the wlieel 
and track, so as to be greater than that 
between the brake shoe and the wheel, sand 
is sometimes poured upon the track wdth 
the effect of producing a greater friction. 
Various forms of sand hoxes have been de- 
vised for sprinkling a small quantity of 
sand directl}^ beneath the wlieel on the 
track where it is required. One of these 
forms is shown in Fig. 54. * The sand box 



132 



ELECTRIC STREET RAILWAYS. 



Sj is mounted within tlie car close to tlie 
platform. The motorman, by pressing with 
his foot upon the foot-button i^, depresses 
the lever L, which is pivoted at jP, and 




Fig. 54.— Sand Box. 

thus causes the rod H, to move forward in 
the direction of its length against the ten- 
sion of the spiral spring G. This opens 
the valve outlet and allows sand to pour 
through the tube T^ upon the track 
beneath. 



CARS AND CAR TRUCKS. 133 

On the truck of a car there is mounted a 
car body familiar to all our readers. These 
bodies are of four types ; namely, the open 
or summer car, the closed car, the converti- 
ble car, and the double decker. The latter 
is not in use on overhead trolley lines. 



CHAPTEK VI. 

ELEOTEIC LIGHTIl^a AND HEATIIN^G OF CARS. 

The advantages possessed by electric 
lightings as obtained from incandescent 
lamps, are so evident, that this method of 
artificial illumination is almost invariably 
employed in trolley cars. The current 
required for the lighting of these lamps is, 
of course, taken from the same source 
which drives the car, that is to say, a 
special circuit is taken from the trolley to 
the track, through the lamps to be lighted. 
The type of incandescent lamp employed 
varies with the number placed in the car. 
If, as is commonly the case, there are five 
lamps, three in the centre and one at each 

134 



LIGHTING AND HEATING OF CAHS. 135 

end, they are connected in series, so that 
the current passes successively through 
each, and they are placed in a special cir- 
cuit directly between the trolley and the 
track as represented in Fig. 55. Here 




Fig. 55. — Diagram of Lamp Circuit of Car. 



the wire leading to the trolley wheel is 
marked Ti\ and enters the switch S^ from 
Avhich it passes through the five lamps 
Xj, Z2, X3, X4, X5, in succession, finally pass- 
ing to the track Tlc^ through the frame- 
work of the truck. 

In this case since the total pressure be- 
tween the trolley and track is app]'oxi- 



136 ELECTRIC STREET RAILWAYS. 

mately 500 volts, and there are five 

lamps in series, the drop in each lamp will 

be 100 volts, the current strength being 

about 2/3rds ampere. The total activity 

developed in the lamps will be ronghly 

500 volts X 2/3rds ampere = 333 watts, 

or less than one-half of a horse-power. 

When nine lamps are employed to light 

the car, in three clusters of three each, all 

nine are placed in one series, the drop in 

50 
each lamp being approximately — =55.5 

tj 

volts. The current strength in this case 

will be a little more than 1 ampere and 

the activity in the lighting circuit will 

be nearly 500, volts x 1.1 amperes = 550 

watts, or 3/4ths horse-power. This activity 

has to be sustained during the operation 

of the cars at night time whether the car 

be rimning or not. If five lamps are 

employed, each lamp must be made for a 



LIGHTING AND HEATING OF CARS. 137 

pressure of roughly 100 volts, while if 
nine lamps are employed, each lamp must 
be made for a pressure of roughly 55 volts. 




Fig. 56.— Car Lamp. 



Fig. 56 shows a common form of lamp 
employed in street cars. Fig. 57 sho^vs 
another form in which the incandescing 
filament is anchored or supported at its 



138 



ELECTRIC STREET RAILWAYS. 



centre for the purpose of preventing the 
filament from being injured by excessive 
vibration. Incandescent lamps for street 




Fig. 57. — Railway Lamp with Ancuoiied or Non- 
Vibrating Filament. 

car use have usually an efficiency of l/ith 
candle per watt ; i. e.^ when operated at 
the pressure for which it is designed^ it 



LIGHTING AND HEATING OF CAES. 139 

gives normally l/itli of a candle per watt 
of activity absorbed, so that a 16 candle- 
power lamp w-ould require normally 64 
watts. 




Fig. 58. — Form of Fixture for 'Car La3^ip. 

A common form of lam^ fixture is 
shown in Fig. 58 and a cluster suitable for 
three lamps is shown in Fig. 59. 



A form of switch for turniuo; the car 
lamps on and off, is shown in Fig. 60. 
This switch box is screwed up inside the 



140 



ELECTRIC STREET RAILWAYS. 



car near the ceiling and has a projecting 
key K^ for turning the lamps on or off. 
The action of th€ key is illustrated by the 
switch shown in Fig. 61, whei'e A and B^ 




Fig. 59.— Form of Three-Lamp Cluster for Car. 

are the binding posts connected to one 
side with the trolley wheel and the other 
with the lamps. On turning the key D^ 
the brass piece C^ may be made to bridge 
metallically across between the posts A 
and B^ thus closing the circuit through all 
the lamps. The switch box, in Fig. 60, 



LIGHTING AND HEATING OF CARS. 141 

also contains a safety fuse or cut-out 
This simple device consists of a wire of 
lead or other alloy that will melt, and 
thus automatically break the circuit, if the 
current becomes excessive. 




Fig. 60.— Savitch and Cut-out for Car Lamps. 



It will be evident that for every 16 
candle-power incandescent lamp operated 
in the car, about 64 watts activity will be 
required; or, roughly, 1/1 2th of a horse- 
power per lamp at the car, which may 
represent say l/8th of an indicated horse- 
power at the engine. 



142 ELECTEIC STREET RAILWAYS. 

When street cars are running in cold 
climates tlie artificial heat required at cer- 
tain seasons of the year may be obtained 
either by the use of an ordinary coal stove, 

D 




Fig. 61. — Switch for Car Lamps. 

or by electric heaters. Although the coal 
stove is the cheaper of the two, yet it pos- 
sesses several inconvenient features. In 
the first place it occupies useful space ; in 
the second place it requires attention and 
introduces more or less dust, smoke or dirt 
into the car, while tlie heat which it gives 



LIGHTING AND HEATING OF CAES. 143 

is principally developed in the upper por- 
tion of the car, the air near the floor 
remaining comparatively cold. Moreo\'er, 
some time is required to start a fire in 
a stove. 

In contrast with these inconveniences, 
the electric heater possesses such marked 
advantages, that, despite its extra cost, it 
has come into use for the heating of electri- 
cally propelled cars. When an electric 
current passes through a wire, heat is de- 
veloped therein. Thus, we have already 
seen that when a current passes through a 
trolley wire, a certain amount of power 
will be expended in heating the- trolley 
wire. Under practical conditions the 
trolley wire will never get sensibly warm 
by the current it carries for the reason 
that the surface it freely exposes to the 
air is so great, that, taken in connection 



144 



ELECTRIC STREET RAILWAYS. 



with its mass, the comparatively small 
amount of heat developed within it is 
rapidly liberated. If, however, the same 
amount of electric resistance which ex- 
ists in a mile of trolley wire, were obtained 




Fig. 62.— Heating Coils of Car Heater. 

in a short length of copper or iron wire, 
then the same amount of heat would be 
produced in a much smaller mass of iron, 
having a greatly reduced surface, with the 
result of producing a much higher tem- 
perature in the wire. 

The coils of wire used in a particular 
form of car heater are shown in Fig. 62. 



LIGHTING AND HEATING OF CARS. 145 

Here the heating coil consists of galvanized 
iron wire which is wrapped in the form of 
a close spiral and then placed in a spiral 
groove on the outside of a porcelain tube. 
This construction affords a great length of 
heating coil in a small space, so supported 
as to prevent the coil changing its form 
when heated and yet practically permit- 
ting neai'ly all of its surface to give oif 
heat to the surrounding air. In the heat- 
ing coil shown in the figure, which is about 
3' 6'' long, there are 392' of wire ; the size 
of wire being No. 20 A. W. G. iron ^vire, 
having a diameter of 0.032", or 32 mils. 
The total surface exposed by the coil 
in a single heater is 1.642 square feet. 
The coil is placed in a metal case, so pro- 
vided with openings as to permit the free 
flo\v of air entering at the bottom of the 
case to flow around the heater, come in 
contact ^vith the heated wire and to 



146 ELECTRIC STREET RAILWAYS. 

escape througli a grating at the top. 
When so desired, the air may be taken in 
directly from the outside of the car. The 
coil in its metal case, ready for fastening 
in position below a seat, is represented in 




Fig. 63. — Electric Car Heater. 

Fig. 63. The heater is sometimes placed 
with its grating flush with the riser be- 
neath the seat. In this case the form of 
heater is that shown in Fig. 64. For cars 
of the ordinary size, four or six heaters are 
employed ; i. ^., two or three on each side 
of the car. The heaters are placed in the 



HEATING AND LIGHTING OF CARS. 147 

risers of the seats near the floor. In Fig. 
65 the interior of a car is shown equipped 
with six heaters, four of which are seen 
beneath the seats at the points A^ B^ C\ D. 



ilihiiiiiliiiiliiiiiiiip 



• llllligCLpiXprXtElCCLLrr^Ir^Lrrr^ 

' 'uhlSiiMiiSBi MSliBiiliili ilHSiiiiMa 



Fig. 64.— FoTiM of Electric Car Heater. 

In order to reo;ulate the amount of heat 
required to meet the changes in tempera- 
ture, a temperature-regidating stmtcli is 
employed, by means of whicli the separate 
heaters may be connected in series or in 
parallel groups between the trolley and 
the track, or by means of Avliich one or 
more of the heaters may be removed at 
will. By this means the amount of cur- 



148 ELECTRIC STREET RAILWAYS. 

rent which passes through the heaters, and, 
therefore, the amount of heat they develop 
can be adjusted. When the switch is 
turned, so as to place all the heaters in 
series, the resistance in the heating circuit 
is greatest and the heat produced is least. 
When all the heaters are employed in three 
parallel groups of two each, the maximum 
current is supplied and the maximum heat 
is obtained. 

Fig. 66, represents the interior of the 
temperature-regulating switch, by which 
these varied connections are made. Fig. 
67, shows the exterior appearance of the 
switch. There are five positions of this 
switch when the current is passing thi'ough 
it, numbered respectively, 1, 2, 3, 4 and 5, 
and the particular position is indicated by 
the numeral appearing through the open- 
ing at W, in the switch casing. The 



I— I 
Q 



H 
» 



O 



O 

d 



o 



St 




150 



ELECTRIC STREET RAILWAYS. 



switcli is SO constructed that before chang- 
ing from one number to another, the cir- 
cuit of the heaters is opened. In position 
5, as shown in the figure, the full current 





-im^M- 


i@ 




_ ^--w.„,- .^!^^^^^^.^;;; 




l^#'^^i| 


^^^M0- 


^ 


^1 





Fig. 66.— Interior Temperature-Regulating Switch 
(Five Intensities). 

strength of about 12 amperes passes 
through the heater, representing a total 
activity of about 500 volts x 12 amperes = 
6,000 watts =: 6 KW = 8 HP approxi- 
mately. This activity is entirely expended 
in heating the wire, and, therefore, in 



LIGHTING AND HEATING OF CARS. 151 

warming the air whicli comes in contact 
witli the wire. Position No. 1, corre- 
sponds to the minimum activity and allows 
about 2 amperes to pass through the 




Fig. 67.— Exterior Temperature-Regulating Switch. 

heater^ representing a total activity of 
about 500 volts x 2 amperes — 1,000 
watts = 1 KW — 1 1/3 HP, approximately. 
In practice, it is found that in cold 
weather about 6 amperes have to be main- 
tained in the heaters, representing an 



152 



ELECTRIC STREET RAILWAYS. 



activity of rouglily 3 KW. The cost of 
producing a KW-Jwur^ or 1,000 joiiles-per- 
second for 3,600 seconds = 3,600,000 Joules, 




Fig. 68.— Car Heater. 



varies considerably witli tlie size of tlie 
electric plant supplying the current, but, 
speaking generally, a fair average may be 
considered as being 1 1/2 cents per KW- 
hour, so that the expense of heating the 
cars electrically during severe weather may 
be estimated roughly as 4 1/2 cents per 
hour. 



LTGTITIIN'G AND HEATING OF CAPwS. 153 



Another form of car heater and its en- 
closino; case is shown in Fio;s. 68 and 69. 



, 5' I* . ! 




f^mmMmmi^i§^ 



Fig. 69. — Car Heater, Designed to Attach to Seat 
Riser. 

This operates on practically the same 
principles. 



CHAPTER VII. 

COIS^TROLLEES AISTD SWITCHES. 

It is necessary in the practical operation 
of a street car to place both its speed and 
the direction of its rnnning under the con- 
trol of the motorman. Moreover, the ap- 
paratus employed to do this should require 
for its operation no more than ordinary 
intelligence, that is, should be capable of 
being operated without any electrical skill 
on the part of the motorman. On electric 
trolley cars, as is well known, the motorman 
controls the car by means of two handles, 
the rio;ht hand one of which controls the 
mechanical brake apparatus and the left 
hand one the electric apparatus called the 

154 



CONTROLLERS AND SWITCHES. 155 

controller. This latter apparatus is con- 
tained within a vertical metal case 
provided on its upper plate with notches, 
corresponding to different speeds of the 
car. By this apparatus the electric cur- 
rent is turned on and off and the power 
and speed of the motor controlled. 

Different systems of electric traction 
employ dift'e,rent forms of controllers, but 
all operate on essentially the same plan. 
It will, therefore, suffice, in pointing out 
the method in which the controller 
operates, to limit the description to a par- 
ticular form in common use. 



The external appearance presented by 
this controller will be seen by an inspec- 
tion of Fig. 70. One of these controllers 
is mounted on the front platform and a 



156 ELECTRIC STREET RAILWAYS. 

similar one on the back platform of the car. 
It is operated by tlie movement of the 
handle H. The small handle \ controls 
an emergency switch used for reversing the 
motion of the car when necessary. Com- 
ing now to the controller, S^ is a stop to 
limit the range of motion of the handle. 
In the position shown the current is turned 
oifj and, as the handle is turned around 
in a clockwise direction, the motors are 
gradually brought into action with increas- 
ing speed, until, when the projection of the 
handle strikes the stop S^ on the other 
side, after nearly one revolution, the maxi- 
mum speed of the car is attained. 

In order to open the controller, a sheet 
iron door is provided, closed with screw 
bolts, which can be manipulated by hand, 
the hinges of these bolts being shown 



CONTKOLLERS AND SWITCHES. 157 



\ 


BH 




^%Jk^ 


.-p 


^^^^^B 


i 


j| 


^ ^ "' 




y 


^ 




mm 




\ 


j^^H 


• 


I 


^- " 











Fig. 70. — Controllek, Closed. 



158 ELECTRIC 3TREET RAILWAYS. 

The interior construction of the con- 
troller is shown in Fig. 71. The lid L Z, 
has been thrown back by withdrawing the 
bolts at the hinges j^ j. By further with- 
drawing the small bolt, J^ shown separately 
beneath the lid, an iron cover C^ hinged 
on the core c^ of the electromagnet M^ is 
also thrown back from the cylinder Y^ 
leaving i,t exposed to view. 

The switch cylinder is turned by the 
movement of the handle H, It carries 
eleven rings of insulating material /^, r^^ i\^ 
etc., upon which are mounted metallic con- 
ducting segments 5i, s^^ s-s, of different 
lengths and in different positions, so that, 
when the cylinder is turned, they come 
into contact at different times with the row 
of eleven fixed contact springs ^j, ^.„ p^^ p,, 
etc. It is these contacts which effect the 
changes in the connections for producing a 



CONTROLLERS AND SWITCHES. 159 



'!;E3'::i!i!!!!iif':!!;ii'a''!i|-!:H^fl'!?!''n;;';:'-ir !;iF 




Fig. 71. — Controller, Open. 



160 ELECTRIC STREET RAILWAYS. 

change in speed of the car. In the posi- 
tion shown, while the handle is at the first 
notch and against its stop, none of the 
segments are in contact with their springs, 
and the trolley is disconnected from the 
motors. The small handle A, rotates a 
small cylinder y, carrying eight sets of me- 
tallic segments and having a row of eight 
fixed metallic contact springs g',, q^^ q^. By 
throwing the handle A, over about 60^, the 
segments in contact with the springs ^, 
can be changed and also the direction of 
the current through the armatures of the 
motors. The direction of rotation of the 
motor can thus be reversed, backing the 
car. At TFJ is a star wheel, Avhich renders 
it necessary that all the successive contacts 
be made and none omitted when the 
handle is turned. 

After contact has been made between 



CONTROLLERS AND SWITCHES. 161 

the motors and the trolley, so as to pass the 
usual current strength through the circuit ; 
then, on breaking contact either at the 
trolley, or at the ends of two wures in the 
circuit on the car, a spark or metallic arc 
will form, which may be from two inches 
to five inches in length. This is the char- 
acteristic arc which is seen when the trolley 
wheel jumps from the wire. It will be 
readily understood that the formation of 
arcs of this character within the con- 
troller, would soon cause its destruction. 
Tliis is avoided in the form of controller 
shown in the figure by means of a device 
called the magnetic hloiv-oitt The current 
through the motors passes through a coil 
wound on the magnet M^ around the iron 
core c. This makes the core <?, a powerful 
electromagnet, and its projection, or pole- 
piece Cj becomes a large magnetic pole. 
AVhen this pole-piece is close down in its 



162 ELECTRIC STREET RAILWAYS. 

normal position tlie polar ridges P^ P^ P^ 
rest close to tlie contact strips pij 2^^'> P^- 
While the motors are running, the magnet 
Mj being excited, produces a powerful 
magnetic flux surrounding the contact sur- 
faces p,^ ^2, ^3. As soon as any break in 
the circuit occurs either in changing con- 
nections during running of the motors, or 
particularly when the current is entirely 
shut off, the severe sparking, which wouhl 
occur, is prevented because the arcs are 
blown out under the influence of the 
ma<:>:netic flux from this mai^net. In other 
words, an arc cannot be maintained in the 
presence of a sufliciently powerful magnetic 
field. 

It remains now to explain the manner 
in which the different positions of the 
handle H^ alter the speed of the car. 
There are altogether eleven notches or sue- 



CONTROLLERS AXD SWITCHES. 163 

cessive positions whicli the handle H^ and, 
consequently, the switch cylinder, can 
assume. The first corresponds as already 
mentioned, to no current, as in Fig. 71. 
There are thus left ten positions, at which 
the speed of the motor can be varied. 

When the handle is pushed to the first 
working position, the segments 5i, s^^ 6?3, 
engage with their corresponding springs. 
The effect of this is to establish the con- 
nections shown in Fig. 72. i?i, i?2, is a 
resistance made up of a coiled insulated 
strip of iron. M^ and M^^ are the motors. 
It is evident, therefore, that the current 
has in this case to pass successively from 
the trolley T^ through the resistance 
-7?!, i?2? ^^^ the two motors to the ground 
G. The resistance _/?i, i?2, may be 1 ohm, 
that of each motor armature 0.4 ohm, and 
that of each field 0.8 ohm. The total 



164 



ELECTRIC STREET RAILWAYS. 



resistance of the circuit between the 
trolley and the track is^ therefore, 3.4 ohms. 

If we assume that the usual pressure is 
steadily maintained between trolley and 



G 




Fig. 72. — Connections Corresponding to First Work- 
ing Notch of Controller. 

track at 500 volts, then the maximum 
current strength which may pass through 
the car circuit under these conditions is, 
by Ohm's law, 500 volts divided by 3.4 



CONTROLLERS AIS^D SWITCHES. 165 

oLnis — 14:7 amperes. lu practice the 
cuiTeut never rises to tliis amount for two 
reasons; namely, 

(1 ) As soon as the circuit is closed, the 
excitation of the field mao;nets causes a 
powerful development of magnetic flux in 
the motors, which momentarily sets up a 
C. E. M. F. tending to check or oppose 
the establishment of the current. This 
C. E. M. F. is of very brief duration, say 
about one second, so that if the motor was 
prevented from running, the full current 
strength according to Ohm's law would 
soon be reached. This is called the 
C, E. M. F, of self-induction ^ because it is 
produced by the magnetic inductive effect 
of the current on its own circuit. 

(2) As soon as current passes through 
the motor it begins to turn and iai so 
doing acts as a dynamo to produce a 
C. E. M. F. which permanently checks the 



166 ELECTRIC STREET RAILWAYS. 

current, and the faster the motor runs the 
greater this C. E, M. F. This G. KM. F. 
of rotation is far more important than the 
C. E. M. F. developed by self-induction, 
since it always operates while the motors 
are running, whereas the C. E. M. F. of self- 
induction only exists during changes in 
current strength. 

It now remains to be explained how the 
C. E. M. F. of rotation automatically 
regulates the strength of current and, 
therefore, the amount of electric activity 
supplied to the car. Let us first suppose 
that the motors are disconnected from the 
car axles, and allowed to revolve freely 
without any friction whatever. If such a 
state of things were possible, the torque, 
or rotary effort of the armature produced 
by the current which first enters them, 
would soon bring the armatures to a high 



CONTROLLERS AND SWITCHES. 167 

rate of speed, under wliicli circumstances 
the C. E. M. F. generated by them would 
be so great that very little current would 
pass through them. Thus, if the total 
resistance of the motor circuit, as shown 
in Fig. 72, was 3.4 ohms, and the amount 
of power required to drive the motors 
light and frictionless, was only 1 HP, or 
say 750 watts, this would mean a cur- 
rent strength of but 1.5 amperes, since 
500 volts X 1.5 amperes = 750 watts. 
In order to limit the current strength to 
1.5 amperes in a circuit of 3.4 ohms, the 
effective pressure must be 5.1 volts, since 

-r— — -. — - = 1.5 amperes. The effective 
3.4 ohms ^ 

pressure between trolley and track must, 

therefore, under these circumstances, be 

only about 5 volts, and this will be pro° 

duced by such a speed of the motor as to 

develop a C. E. M. F. of 495 volts; for, 



168 ELECTRIC STREET RAILWAYS. 

since 500 volts is the E. M. F. supplied, 
and 495 is the C. E. M. F., the difference 
serving to drive the necessary 1.5 amperes 
through the resistance of the circuit will 
be 5 volts. 

If now some small frictional resistance 
or load be applied to the motors; or, in 
other words, if the motors be required to 
do some little work, the activity which 
they will require to be supplied with to 
perform this work may amount to 2 HP 
or, approximately, 1,500 watts (1.5 KW). 
Under these circumstances the current 
strength must increase to 3 amperes, since 
3 amperes at a pressure of 500 volts 
represents the needed activity of 1,500 
watts. In order to permit 3 amperes 
to pass through the resistance of the cir- 
cuit (3.4 ohms) the eft'ective pressure 
must be 10.2 volts, since 10.2 volts -^ 3.4 



CONTROLLERS AND SWITCHES. 169 

ohms = 3 amperes. The E. M. F. applied 
beiDg 500 volts, the C. E. M. F. must be 
490 volts and the speed of the motors will 
drop sufficiently to produce only 490 volts 
C. E. M. F., instead of 495. In the same 
way if we suppose the motors to be 
coupled to their respective car axles, and 
work to be required from them to drive 
the car, to an amount of say 10 HP, 
then the power which must be sup- 
plied to the motors to make up for losses, 
both frictional losses in the gears and 
bearings, and electrical losses in the arma- 
ture and field coils, may be 15 HP, or 
15 X 746 = 11,190 watts = 11.19 KW. 
This is the electric activity which must be 
supplied from the circuit to the motors, 
and will represent a current strength of 
22.38 amperes at a pressure of 500 volts. 
The effective pressure required to drive 
22.38 amperes through a resistance of 3.4 



170 ELECTRIC STREET RAILWAYS. 

olims, will be 76.09 volts. The C. E. M. F. 
required to limit the effective pressure to 
approximately 76 volts, will be 500 — 76 
== 424 volts, and the motors will drop in 
speed until this is the C. E. M. F. which 
they supply. 

Proceeding in this way, the more load 
we put on the motors ; L ^., the more we 
load the car, or the steeper the grade it is 
necessary to ascend, the greater the electric 
activity which must be supplied to drive 
the car, and the greater the current 
strength which must be passed through 
the motors to produce this activity. 
Under these circumstances the motors will 
continue to slacken in speed so as to per- 
mit the current to pass, and will always 
attain such a speed as will permit the 
required activity to enter them in order to 
perform the work they have to do. When, 



CONTROLLERS AND SWITCHES. 171 

finally, the load is so great that the motors 
are unable to run, the activity received 
will be that defined by Ohm's law, shortly 
after the circuit is closed. In tliis limiting 
case, all tlie activity is expended as heat in 
the resistance M^^ JR^^ and in the motors M^ 
J\L In all other cases, when tlie motors 
are running, some of the activity is devel- 
oped as heat, but by far the greater part is 
developed as mechanical activity in pro- 
pelling the car. 

On the other hand a reduction in the 
load of the motors must be followed by an 
increase in their speed. This increase, how- 
ever, will be arrested as soon as the C. E. M. 
F. is increased to the value w^hich limits the 
current strength to that required for the rate 
at which work is being mechanically done. 

In all cases it will be evident that the E. 



172 ELECTRIC STREET RAILWAYS. 

M. F. existing between the trolley and the 
track, which we have assumed to be 
maintained at 500 volts, is to be met by 
an equal total C. E. M. F. in the car circuit 
T, G. If the motors are at rest, this C. E. 
M. F. must be entirely due to drop in the 
resistance, represented by the product of 
the current strength in amperes and the 
resistance in ojims. For example, with the 
car held at rest, we know that the current 
will be 147 amperes in the case of Fig. 72, 
and this multiplied by the total resistance 
of 3.4 ohms, represents a drop of pressure 
amounting to 500 volts. 

V/hen, however, the motors are running, 
their C. E. M. F. of rotation will necessi- 
tate a smaller drop in the resistance of 
their circuit. Thus, if the motors are pro- 
ducing together a C. E. M. F. of 400 volts, 
then the drop in the resistance J?i, i?2? ^^'iH 



CONTROLLEKS AND SWITCHES. 173 

be only 100 volts, and if the motors pro- 
duced together a C. E. M. F. of rotation of 
490 volts, the drop will be reduced to 10 
volts. The activity available for mechani- 
cal work is the product of the C. E. M. F. 
of rotation and the current strength. For 
example, if the motors in Fig. 72 develop to- 
gether a C. E. M. F. of rotation amounting 
to 490 volts, and the drop in the resistance 
of motors and rheostat is, therefore, 10 
volts, the current strength, which will pro- 
duce this drop, will be by Ohm's law 

10 volts ^ f., '4-1 

m 2.94 amperes, approxnnately. 

3.4 ohms i ^ ii ^ 

The total activity taken from the circuit 
between 2^ and G^ will, therefore, be 500 
volts X 2.94 amperes = 1,470 watts. Of 
this, the amount capable of producing me- 
chanical activity is 490 volts X 2.94 amperes 
= 1,440 watts, while that only capable of 
producing heat is 10 volts X 2.94 amperes 



174 ELECTRIC STREET RAILWAYS. 

= 29.4 watts. It is evident that the 
greater the proportion of C. E. M. F. of 
rotation to the drop in the circnit T^ G^ 
for any given current the greater will be 
the activity used for propelling the car. 

We will now explain the use of the resist- 
ance .^i, ^2. In the first place if the resist- 
ance J?i, _^2, be removed from the circuit in 
Fig. 72, the total resistance between T^ and 
G^ will be reduced to 2.4 ohms, and the 
possible current strength by Ohm's law, 
such as would exist when the car was 
absolutely prevented from moving, would 

, 500 volts ^^^ 

be ;^, — 1 — - = 208 amperes, approxi- 
2.4 ohms ^ ' li 

mately. In other words, a current of 208 

amperes would maintain a drop of 500 

volts in a total resistance of 2.4 ohms. 

The first rush of current would, tlierefore, 

be greater, and the current strength dur- 



COTTTROL'LERS AND SWITCHES. 175 

ino; the time when tlie motors were acceler- 
atiiig and reaching then* limiting speed of 
rotation would be greater, so that the car 
would start from rest with a greater Jerk, 
and, moreover, waste a greater amount of 
power in the process. The greater the 
amount of resistance which is introduced 
into the circuit of the motors at the start, 
the smaller the current which will pass 
through them, the more quietly the car Avill 
start and reach the speed which limits the 
C. E. M. F. of rotation, and the less the 
activity w^hich will be wasted during that 
period in which the motors are accelerating 
up to this speed. 

On the other hand, the continued use of 
a resistance i?i, 7?2 is more or less wasteful 
after the car has been brought up to speed, 
because it produces a drop in the circuit 
and prevents the C. E. M. F. of rotation 



176 ELECTRIC STREET RAILWAYS. 

from coming into full play. For example, 
if the cmTcnt wliicli the circuit must re- 
ceive under given conditions of load is 50 
amperes, the drop in the resistance of 1 
ohm at ^1, i?2, will be 50 amperes X 1 
ohm — 50 volts, and the effect is tempor- 
arily the same as though the motors J/j, 
M^^ were connected to the trolley circuit 
between T and G^ without a resistance, 
but with 450 volts pressure. The activity 
exjjended in the motors, both as drop in 
their resistance, and as available energy 
against their C. E. M. F. of rotation, will 
be 450 volts X 50 amperes = 22,500 watts. 
The circuit between Tand G^ supplies a 
total activity of 500 volts X 50 amperes = 
25,000 watts. 

The effect, therefore, of constantly main- 
taining the resistance Jx^^ H^^ in the circuit 
of Fig. 72, is to expend activity in it as 



CONTROLLERS AND SWITCHES. 



177 



heat, and thus prevent the motors from 
reaching as high a speed as they otherwise 
would, while, of course, it is an advantage 
to be able to run slowly, it is nevertheless 




Fig. 73. — Street Car Resistance Coil. 

a disadvantage to waste power in the re- 
sistance for this purpose. The use of a 
certain amount of resistance is, therefore, 
beneficial during periods of starting, and 
where the advantage of running at low 
speeds offsets the disadvantage of Avasting 
power. 



178 ELECTRIC STREET RAILWAYS. 

The resistance R^^ H^i is commonly made 
in the form shown in Fig. 73. Here the 
coils are placed in an iron box of such 
dimensions as to permit it to be attached 
by screws or bolts at the lower part of the 
car body. It is purposely left open to per- 
mit the circulation of air and thus carry off 
the heat generated in the coils. 

Let us now inquire what happens when 
the controller is turned to the next or sec- 
ond working notch. The effect of this is 
shown diagrammatically in Fig. 74. An 
inspection of the jfigure will show that half 
the extra resistance is cut out of circuit ; 
namely, H^. This has the effect of reducing 
the drop of pressure in the resistance for a 
given current strength passing through the 
circuit. Consequently, the motors have to 
rim faster to make up the total C. E. M. F. 
of 500 volts, so that the speed of the car is 



CONTROLLERS AND SWITCHES. 



179 



increased. For example, if in tlie case of 
Fig. 72, a drop of 100 volts occurs in the 
resistance R^y i?2> requiring 400 volts to be 




Fig. 74.— Connections Corresponding to Second 
Working Notch of Controller. 

made up by the motors in C. E. M. F. of 
rotation and drop in their resistances, then, 
when the resistance H^^ is cut out, as in Fig. 



180 ELECTEIC STEEET EAILWAYS. 

74, with the same current strength there 
will be only 50 volts drop in that half of 
resistance J?2? remaining in the circuit, and 
450 volts must be made up by the two 
motors in C. E. M. F. of rotation and 
drop ; they will, therefore, increase in speed 
to this extent. Consequently, the effect of 
cutting out resistance from the circuit is to 
cause the car to increase in speed to an ex- 
tent which will depend entirely upon the 
amount of drop reduced, which in its turn 
will depend upon the load of the car. If 
the car is very light, and is steadily running 
on a level portion of the track, the drop in 
the resistance will be very small and the 
eft'ect of halving this drop will be very 
small, so that the car will receive very lit- 
tle increase in its steady speed by moving 
to the second notch. If, on the contrary, 
the motor is heavily loaded, or is running 
up a steep grade, there will be a heavy 



CONTUOLLEllS AND SWITCHES. 181 

drop iu the resistance i?i, 7?2, especially on 
starting^ due to tlie stronger current and 
greater activity required, so that cutting 
out half the resistance and drop will pro- 
duce a greater increase in speed. 

Fig. 75, shows the effect of turnins; the 
controller handle to the third notch. Here, 
as will be seen, all the resistance R^^ R^i ^^ 
cut out, so that the motors have to make 
up in drop and C. E. M. F. of rotation, the 
full line E. M. F. existing between trolley 
and ground. They will, therefore, require, 
other thino-s remainino; the same, to main- 
tain a higher speed than in either of tlie 
preceding positions of Figs. 72 and 74. 
The total resistance of their circuit between 
Tand Gy is 2.4 olims. . 

Turnino; the controller handle to the 
next, or fourth working notch, the effect 



182 



ELECTRIC STREET RAILWAYS. 



produced is represented diagrammatically 
in Fig. 76. Here, as in Fig. 75, the extra 
resistance is entirely cut out and in addition 



A/va/vvOnaaaa/> 




Fig. 75.— Connections Corresponding to Third 
Working Notch of Controller. 



the field magnet coils of each motor are 
provided with a hy-path or slivnt S^, /S2, so 
that the current through the circuit divides 



CONTROLLERS AND SWITCHES. 



183 



at each field magnet, a part only going 
tlirouo;li the mamiets, and the remainder 
going around through the shunt, all of the 



E. Ex 




Fig. 76. — Connections Corresponding to Fourth 
Working Notch of Controller. 

current, however, passing through each 
armature. 



The effect of shuntino; the field mao;;ne- 
tizing coils is to weaken them ; ^. ^., has 



184 ELECTRIC STREET RAILWAYS. 

the same effect as taking wire off' the coil, 
or of reducing tlie equivalent current 
strength. The magnetism produced by 
the field magnets of the motors, will, 
therefore, be reduced, and in order to 
make up a given C. E. M. F., with this 
reduced magnetism, a greater speed must 
be attained by the armatures. The car 
has, therefore, to run faster owing to the 
introduction of the shunts. At the san^ 
time, if the grade and load remain the 
same the greater speed of the car will call 
for a greater expenditure of mechanical 
power, and, consequently, a greater ex- 
penditure of electric current and activity, 
so that, since each motor is called upon to 
produce a total C. E. M. F. of 250 volts 
in drop and in rotation, this C. E. M. F. 
will be developed by a greater speed in 
the weakened magnetic fields, but with a 
greater current supply and to that extent 



CONTROLLERS AND SWITCHES. 185 

a greater drop ; for, if the current strength 
supplied was insufficient to maintain the 
increased activity of the car, then a de- 
crease in speed would occur until the cur- 
rent supply was made up. 

The connections corresponding to the 
fifth working notch are the same as those 
shown in Fig. 74, that is to say, the re- 
sistance i?2, is first restored to the cii'cuit 
before changing the connections at the 
next step. 

The condition of affairs when the con- 
troller is turned to the sixth working 
notch is represented in Fig. 77. Here, it 
will be observed that the shunts around 
the field magnets are w^ithdrawn, and the 
resistance Jtg, is restored to the circuit, 
while the second motor 3i^, is completely 
cut out. The first motor Jt/j, has now to 



186 



ELECTRIC STREET RAILWAYS. 



make up the full pressure of the line with 
the aid of the drop in half the resistance. 
Excluding the drop in the resistance J?^, 



R. 



Rx 



AAAAAACIAAVv\A 




Fig. 77.— Connections Corkesponding to Sixth 
Working Notch of Controller. 



the speed Avill be roughly double that 
corresponding to the connections in Fig. 
75 ; for, the single motor armature must 
produce, roughly, double the C. E. M. F. 



CONTROLLERS AND SWITCHES. 187 

of rotation that it produces when it was 
aided by the motor J/g. 

The connections of the seventh working 
notch are the same as for the sixth, or re- 
main as shown in Fig. 77. This is merely 
for the pnrpose of not making the next 
change too suddenly, requiriog the motor- 
man to take a certain time in turning his 
handle for two notches, so as to avoid 
abrupt changes in speed. 

The conditions produced when the 
eio;hth workino; notch is reached ai^e 
indicated diagrammatical ly in Fig. 78. 
Here the second motor Jt^^, which was 
withdrawn from the circuit in Fig. 77, is 
replaced ^/^^ara/M with J/j, instead of in 
series ; that is to say, the current through 
the circuit divides, half passing through 
J/j, and half through M^, Each motor, 



188 



ELECTRIC STREET RAILWAYS. 



however, must make up, disregarding drop 
in H^j the full pressure of 500 volts be- 
tween trolley and track, and the speed of 
rotation would remain practically un- 



R. 



R. 



sAAAA/Viw^VvAV 




PiGc 78. — Connections Corresponding to Eighth 
Working Notch of Controller. 

changed, except that the current, being 
approximately halved through each mag- 
net, the strength of the magnetic field is 
weakened, and the armatures have to run 



CONTROLLERS AND SWITCHES. 



189 



faster to make up tlie required C. E. M. F., 
in this weakened magnetism. The speed 
of the car will, therefore, be greater than 
in the case represented in Fig. 77. 



R» R* 

AAA/VNAQAAAAAA ' 




Fig. 79. — Connections Corresponding to Ninth 
Working Notch of Controller. 



The effect of turning the controller 
handle to the ninth working notch is rej)re- 
sented in Fig. 79. Here the resistance -Z?^, 
is completely cut out of circuit and the 
two motors are in parallel as in the last 



190 



ELECTRIC STREET RAILWAYS. 



case ; or, as it is sometimes called, are con- 
nected in multiple. The speed will be 
increased, owing to tlie fact that the drop 
previously existing in R^i ^^^^ requires to 
be made up by the motorpi alone. 



R. 



R. 



aAaaaaPaaaaaa 




Fig. 80.— Connections Corresponding to Tenth 
Working Notch of Controller. 



Fig. 80, represents the connections cor- 
responding to the tenth and last working 



CONTROLLERS AND SWITCHES. 191 

notch ; ^. ^., the connections for full speed. 
Here the only change from the connec- 
tions of Fis;. 79 lies in the restoration of 
the shunts around the field magnets^ thereby 
reducing their excitation and requiring 
an increased armature speed in order to 
maintain the C. E. M. F. Each motor, as 
before, has to produce, in C. E. M. F. and 
drop, the full pressure of 500 volts, and 
when the field is weakened, the speed for 
a p;iven C. E. M. F. of rotation has to 
increase. 

It will be observed, therefore, that the 
movement of the controller handle through 
the successive notches, results in an in- 
creasing speed of the car. Of course 
movement in the 023posite direction results 
in changing the connections in opposite 
order of succession ; and, consequently, 
slows the car. 



192 ELECTRIC STREET RAILWAYS. 

There is no definite or precise speed 
whicli corresponds to each notch, since that 
will depend upon the load of the car and 
the gradient at which it runs. In other 
words, it will depend upon the activity 
which the motors exert. The lighter the 
load for any given notch or set of connec- 
tions, the faster the motors will run. On 
the contrary, an increase of load at any 
time, even without touching the controller 
handle, will result in a diminution of 
speed. 

The function of the small handle A, is to 
reverse the direction of current through the 
two motor armatures, and, consequentl}^, 
to reverse their direction of I'otation. 
As this cannot be safely accomplished 
during the running of the motoivs, the 
handle A, is so arranged mechanically that it 
cannot be turned until the controller handle 



CONTROLLERS AND SWITCHES. 193 

H^ is at the ^^ oft' position " on tlie first 
notcli ; so that before the car can be reversed 
the current must first be shut off. This 
prevents any arcing on the contacts of the 
reversing cylinder y. All the arcs which 
tend to form on the contact segments of 
the large cylinder are extinguished by the 
action of the magnet J/, which is always 
in the circuit. 

At the bottom of the controller are two 
switches m and n^ respectively. These 
are commonly employed to cut out one of 
the motors on the car, if by any accident 
it should become disabled. For example, 
if the brushes of motor J/^, should fail to 
make good contact, or give other electrical 
trouble, that motor can be entirely cut out 
of circuit. Similarly, by lifting the switch 
handle n^ the motor J/^, can be entirely cut 
out of circuit. In such a case the car is 



194 



ELECTRIC STREET RAILWAYS. 



operated by the remaining motor, and 
only such notches can be used with the 
controller handle as wil] be available for 
the operation of that motor. 



|i^r--^-«*-T-; .:■,.■...-■•■:■ 


mJ^ ' 


r;- :^::^ ^^ 


^£— J 








^^^^^ ' 


iiliift- . ^^R 


^^H^'l'! ' 


9K^i ' ;''''^^H 


■1 


illli ',^^H 


HH^ij^^: 


:,,,'';'.;; jf?^;^^^^H 


Pi^»?, 



Fig. 81.— Street Car Controller. 



Another foiTn of controller is shown 
in Figs. 81 and 82e Here, as before, we 



COIS^TROLLERS AND SWITCHES. 



195 



have the main controller handle H^ and a 
small reversing handle A. The method of 
operation is substantially the same in 




Fig. 82.— Controller of Fig. 81 Opened for 
Inspection. 

all controllers. In this case, however, 
no attempt is made to blow out the arcs 
magnetically when breaking the circuit. 
Instead of this the arc is caused to occur 



196 



ELECTRIC STREPrr RAILWAYS. 



simultaneously at a number of segments in 
series, so as to produce a number of small 
arcs instead of a single large one. This 
greatly reduces the heat and deflagrating 




Fig. 83. — Form of Controller Resistance. 

power of the arcs. The contact points 
at which they occur are renewed from 
time to time. 



Fig. 83, shows a form of resistance 
employed with the controller represented 



COISTTROLLERS AND SWITCHES. 197 

in Figs. 81 and 82. Here the resistances 
are formed of strips of sheet iron, wound 
upon insulating frames, in coils or 
cylinders, three of which are stowed in the 
iron box shown, in such a manner as to 
allow free circulation of air to carry off 
the heat that may be generated in them. 
There are four screw terminals ^j, t^, t^, t^, 
placed on an insulating slab at the top 
of the case for the wires to connect with. 

The controller of a car may be regarded 
as a complex switch capable of effecting 
the different connections such as we have 
indicated. Usually there is one controller 
at each end of the car. The handle H^ 
is cari'ied from one controller to the other 
accordinoj to the direction in which the car 
is to be run. 

In order to protect the controller or 



198 



ELECTRIC STREET RAILWAYS. 



motors from any excess of current, an 
automatic cut-out or safety fuse is employed 
in the circuit. This consists of a copper 
wire, of such size that it will melt when 
the current attains an excessive strength. 




Fig. 84.— Fuse Block. 

The wire is enclosed in a box or block 
called a fuse hloch^ placed in a suitable 
position on the car, usually on the plat- 
form overhead, where it can be readily 
inspected. A form of fuse block is repre- 



sented in 



Fig. 



84. The block, as it 



COITTROLLERS AND SWITCHES. 199 

appears wlien closed, is shown at 6^ and, as 
it appears open, at 0, A block of hard 
wood B^ carries, secured to its edge, two 
screw binding posts /Si and S^^ and tongues 
^1, Tg. The clips are permanently in con- 
nection w^ith the trolley on one side, and 
the controller on the other, so that the 
current has to pass from the trolley 
through the fuse block by means of these 
clips. Connection is made between the 
clips through a wire, usually either No. 
12, or No. 14, A. W. Gr., running around 
the edge of the block B^ and having its 
extremities clamped under the screw^s s^ 
and ^2. The lid Z, of the box, as well as 
its interior, are lined with asbestos cloth to 
prevent damage through the melting of 
the copper fusee 

In addition to the controller and fuse 
block there is usually added a canopy 



200 ELECTKIC STREET RAILWAYS. 

switch at each end of the car. This switch 
is provided for the purpose of permitting 
the motorman to turn the current on or off 
the car as desired, when, for example, he 
wishes to inspect a fuse block or con- 
troller, without pulling down the trolley 



k'-,' " ' ^ 




--,- - . , -, 


- \ 


|-f. , 


''''''-' 'a 


^ 


L 




M|:| 


Wk 


\--y 




Wmm 


*!^ 


« - 


• '.''HH| 


wmm 




■■P 


J.._;^LK.r;,i.,.,.x .., 






_ 



Fig. 85. — Canopy Switch. 

pole. It receives its name of canopy 
switch from its position beneath the 
canopy or roof of the platform. 

Fig. 85, shows a form of canopy switch. 
A cast iron box B^ encloses the working 



COMTROLLERS A^ND SWITCHES. 201 

parts and screws up against the canopy. 
The handle H^ projects from this box and 
can be moved sideways in the slot or groove 
provided for the purpose. This insulat- 
ing handle is fastened to a metallic blade 
which closes a contact with a clip C, thus 
establishing the main circuit from the 
trolley to the controller. S^ jS, are two 
slotted slabs between which the handle 
plays. 

To protect the motors and apparatus on 
a street car from electrical discharges pro- 
duced by atmospheric disturbances ; i, e., 
from lightning discharges, a lightning 
arrestor is usually included in their equip- 
ment. A form of lightning arrestor is 
represented in the accompanying figure 86. 
Here a cast iron box S^ B^ wath its lid 
X, X, removed for inspection of its inte- 
rior, has a pair of marble slabs, the upper 



202 



ELECTRIC STREET RAILWAYS. 



one of which, is shown at M^ clamped 
together by screws. A groove runs down 
their interior surface, between two metal- 




FiG. 86. — Lightning Arrestor. 

lie pieces c^ and c^^ in electrical connection 
with the leads or insulated conducting 
wires 6^, C^. This groove is black-leaded 



CONTROLLERS AND SWITCHES. 203 

in such a manner as to provide a ready 
path foi' discharges of very high E. M. F., 
such as those which accompany lightning 
discharges, but forms an effectual barrier, 
or high resistance path, to currents from a 
pressure of 500 volts. Should a lightning 
discliarge occur between the trolley wire 
6^1, and the ground or track wire 6^? the 
dynamo current wall be unable to follow 
this discharge owing to the rapidity with 
which the heated column parts with its 
heat to the marble blocks. In otlier 
words, the conducting path is chilled so 
suddenly, after the passage of the momen- 
tary high-pressure discharge, that the 
dvnamo current is unable to follow. If 
this were not effected the high-pressure 
discharge would establish a very powerful 
and dangerous arc between trolley and 
track. 



CHAPTER YIII. 

TEOLLEYS. 

The existing system of trolleys and 
trolley wires for street railway cars, simple 
as it seems, lias, nevertheless, been tlie out- 
come of no little practical development 
and experience. At tlie present time tlie 
system in almost universal use is the 
single-trolley system. In this system, a 
current is taken from an overhead wire 
suspended over the street. After passing 
through the motors the current returns to 
the power station, through the track and 
ground return. 

The well known mechanism provided 

204 



TROLLEYS. 205 

for transferring; the current from the trol- 
ley wire to the cars, called the trolley mecli- 
anism^ is shown in Fig. 87. As will be 
seen, it consists of a light steel jjole p^ 
called the trolley i^ole^ mounted on a base 
^, called the trolley hase^ and provided at 
its extremity with a light wheel t^ called 
the trolley lolieeL The rope r^ called the 
trolley rope^ is provided for pulling the 
trolley away from the trolley wire w %o^ 
and for aiding in replacing it. 

Simple as the trolley mechanism appears, 
nevertheless, certain conditions must be 
satisfied, in order to ensure efficient opera- 
tion. One of the most important of these 
is that sufficiently firm pressure or con- 
tact be steadily maintained between the 
trolley and the wire under which it runs. 
Moreover, this contact must be flexible. 
The requisite flexibility is obtained both 



206 



ELECTRIC STREET RAILWAYS. 



^■^^^^1 



:'W 




Fig. 87. — Passenoer Car with Trolley. 



TROLLEYS. 207 

by the flexibility of the trolley wire itself, 
and the monuting or support of the trolley 
on its base. Means too, are provided for 
reversing the direction of the trolley pole, 
so that the car may be driven in either 
direction. For obvious mechanical reasons 
the trolley pole always slants away from 
the direction in which the car moves. 

The trolley lolieelj or trolley^ is the name 
given to the revolving part which is sup- 
ported at the top of the trolley pole, and 
maintained in rolling friction npon the 
nnder side of the trolley wire. Its func-. 
tion is to maintain electric contact with 
the wire, so as to take from it the current 
required for the operation of the car. 
One form of trolley wheel is seen in Fig. 
88, As here shown, it consists of a light 
wheel W^ usually of gun metal, sup- 
ported in di frame or hary H^ and running 



208 



ELECTRIC STREET RAILWAYS. 



freely upon a spindle^ not shown in the fig- 
ure, passing through both harp and wheel. 
The grooved form given to the wheel not 
only serves the purpose of ensuring a 




Fig. 88. — Trolley Wheel and Harp. 

more extended rolling contact surface 
w^ith the wire, but also serves to prevent 
the trolley from slipping off the wire. The 
spring %D^ pressing against the face of the 
trolley, maintains good electric contact 
between the wheel and an insulated wire 



TROLLEYS. 



209 



which passes down through the trolley 
pole to the car. 




Fig. 89.— Form of Trolley Wheel. 

Various forms of trolley wheels have 
been devised. It is essential that they 




Fig. 90.— Form of Trolley Wheel. 



210 ELECTRIC STREET RAILWAYS. 

shall be as light, rigid and freely running 
as possible. For tins purpose, special 
attention is paid to their lubrication, 
which is usually effected by employing a 
bushing of graphite, or other lubricating 
material. 




Fig. 91.— Section of Tkolley Wheel, Showing 
Lubricating Eushing. 



As an illustration of some of the various 
forms of trolley wheels those shown in Figs. 
89 and 90 may be taken. It will be ob- 
served that these wheels are ribbed, so as 
to ensure strength combined with light- 



TKOLLEYS. 211 

ness. Moreover, should the rim of the 
wheel wear out and drop off dui-ing a 
trip, the trolley wire will still be 
gripped by the ribs R, B. The busliing 
of lubricating material is seen at h^ Fig. 91, 
which shows a section throuorh the wheel of 




Fig. 92.--LUBRICATING Bushing. 

Fig. 89. Here the lubricating bushing i?, 
is seen in place at the centre of the hollow 
Avheel. Fig. 92 shows a form of bushing 
ready for insertion. 

At times during winter, when the 
trolley wire is covered with sleet, some 
difficulty is experienced in taking off the 



212 ELECTRIC STREET RAILWAYS. 

current, ice being practically an insulator. 
Various devices have been suggested to 
avoid this difficulty. A form of trolley 
wheel, which assists in clearing sleet from 
the wire, and allows the fragments of ice 




Fig. 93.— Sleet-Cutting Tkolley Wheel. 

to escape through the sides of the Avheel 
is shown in Fig. 93. 

The trolley pole is in almost all cases a 
steel tube, tapering toward the top. Its 
lower end is mounted on the trolley 
frame or base. Springs are connected 



TROLLEYS. 



213 



between the base and tbe pole in such a 
manner as to maintain the pole in contact 
with the wire, with a nearly uniform pres- 
sure, under all conditions of dip or devi- 
ation of the trolley wire. Various trolley 




Fig. 94.— Trolley Base. 



IS 



poles and bases have been employed, 
well known form of trolley base 
shown in Fig. 94. Here the pole P^ 
terminates in a fork attached to a pair 
of sectors S^ S, forming a frame, capable 
of revolving about a vertical axis Vj 



214 ELECTRIC STREET RAILWAYS. 

SO as to accommodate the pole and trol- 
ley wlieel to turns or curves in the 
track and trolley wire. The six spiral 
springs G^ maintain a tension upon these 
sectors tending to force the pole P^ 
upwards. This tension can be altered by 
the screw adjustment behind the springs. 
In oi'der to be able to use the trolley 
when the direction of the car is reversed, 
the pole is first pulled down from the 
trolley wire and then swung around the 
vertical pivot V^ when it is allowed to 
re-engage with the wire in the opposite 
direction. 

Another frame and pole called the 
Boston trolleij apparatus is represented in 
Fig. 95. The wooden frame F F F F, 
is screwed to the roof of the car. It 
carries a spindle^ working on a horizontal 
axis and bearing the pole P. at its centre. 



TROLLEYS. 



215 



Eight spiral springs G^ G^ maintain tlie 
requisite tension npon tlie pole under 
the screw adjustment s s. Two smaller 
spiral springs g^ g^ are provided for sup- 
porting the pole in the vertical plane, and 




Fig. 95.— Boston Trolley Base and Pole. 

help to keep it from leaving the wire. T, 
is the trolley ; H^ the harp ; r^ the attach- 
ment ; and P, the pole. 

A simple form of trolley base is shoAvn 
in Fig. 96. Here the pole P, is sup23orted 



216 



ELECTRIC STREET RAILWAYS. 



in a fork i^, carrying two lugs 7, l^ con- 
nected on each side of the pole by rods to 
the extremities of stout spiral springs. 
The effect of these springs is to maintain 
the trolley pole vertical under ordinary 
circumstances, and, when the pole is 




Fig. 96. — Form op Trolley Base. 

pulled down, it tends to return to the 
vertical position by the compression of 
one spring and the distension of the other. 
The pole and springs together can swing 
around the vertical axis upon which they 
are mounted so as to accommodate the 
trolley to curves. 



TROLLEYS. 



217 




Fig. 97.— Trolley Pole and Base. 

Other forms of trolley j^oles and bases 
are shown in Figs. 97 and 98. The rnech- 




FiG. 98.— Trolley Base. 



anism is sufficiently clear in each case 
to be understood by a mere inspection. 



218 ELECTRIC STREET RAILWAYS. 

The angle wliicli tlie trolley pole makes 
with the roof of the car, under orclinarj 
circumstances, is about 40^. The trolley 
wheel is ordinarily pressed upward with 
a force of about 30 pounds weight against 
the wire. 



CHAPTER IX. 

TEOLLEY LESTE COIN^STRUCTION'. 

The poles which support the trolley 
wire over the track are either of wood or 
of iron. In the country, wooden poles are 
frequently employed, while in cities iron 
poles are preferred. The methods most 
frequently used for supporting the trolley 
wire are either by the use of span to ires or 
by hrachets. Span-w^ire construction re- 
quires poles in pairs, on opposite sides of 
the street, while bracket suspension only 
necessitates a single line of poles even for 
double tracks. AVhere, however, bracket 
poles are used for double tracks they are 
open to the objection of requiriog to be 

219 



220 



ELECTEIC STREET RAILWAYS. 



placed in the middle of the street, thus 
tending to obstruct traffic. 

Fig. 99, shows the span-ivire systein^ 
with two iron poles, P, P, made of three 




Fig. 99. — Span-Wire Support. 



tapering lengths of iron tube, s^ s, is the 
span wire, commonly of No. 1 A. W. G. 
iron wire ; n, n, are the insulators sup 



TROLLEY LINE CONSTKUCTION. 



221 



ported on the span wire, and in their turn 
supporting the two trolley wires over 
their respective tracks. The poles are 





Fia. 100.— Bracket Pole for Double Track. 



commonly 27 to 30 feet long, and are 
buried to a depth of 6 feet, being usually 
set in concrete. For spap-w^ire construe- 



222 



ELECTRIC STREET RAILWAYS. 



tion, the poles are commonly set slanting 
from the tracks so as to enable them 
better to stand the strain of supporting 
the trolley wires. 




Fig. 101. — Single-Track Bkacket Support. 



The poles for the hracket'Support system 
are always set vertically and midway be- 
tween the tracks. Such a pole is shown 
in Fig. 100. Here h^ Z>, is the bracket arm 
and fly Uy the insulators suspended there- 



TROLLEY LINE CONSTKUCTION. 



223 



from, supporting in tlieir turn tlie trolley 
Avires w, w, and w, to. 

Forms of single-trach bracket suspension 
are shown in Figs. 101 and 102. The 




Fig. 102.— Single-Track Bracket Support. 



poles are set about 120 feet apart ; i. e., 
about 45 per mile with bracket suspen- 
sions, or 90 per mile for span-wire sus- 
pension. 

In order to attach the span wires to the 



224 ELECTRIC STREET RAILWAYS. 

iron pole, iron clamps are employed, 
generally of the form shown in Fig. 103. 
When the* clamps are in position facing 
each other on opposite sides of the street, 
the span wires are stretched between them 




Fig. ly03.-~PoLE Clamp. 

under considerable tension, depending 
upon the weight of trolley wire, but 500 
pounds weight is a fair tension. Where 
only a single span wire crosses the street, 
it is often stretched between insulators at 
the top of the poles, as shown in Fig. 99. 

Since, of course, the trolley conductor is 



TROLLEY LINE COISrSTRUCTION. 225 

an uninsulated wire, guard vnres are often 
employed to prevent damage from con- 
tact with bare telegraph or telephone 
wires, which would thereby become con- 
nected with a pressure of 500 volts. 
Guard wires are of two kinds ; viz., S2ya}i 
guard tvireSj which cross the street im- 
mediately above the span supports over 
the trolley wire, and running guard loires^ 
which run parallel with and immediately 
over the trolley wires to receive and inter- 
cept any wire falling from above. The 
relative position of guard and suspension 
wires is illustrated in Fig. 104. P, P, are 
opposite poles, c^ Cj the pole clamps, 
e§, 5, the suspension span wire, and g^ g^ 
the guard ^pan wires. The trolley wires 
are always suspended from the lower 
wire ^, ^, and guard wires are usually sus- 
pended over the trolley from the upper 
span g, g. 



226 



ELECTRIC STREET RAILWAYS. 



We will now turn our attention to the 
devices adopted both for supporting the 
trolley wire from the suspension span wire, 
and foi' enabling the trolley to be stretched 

P Pd 





Fig. 104.— Poles with Guard and Suspension Span 
Wires. 

tightly. It is necessary not only to sup- 
port the wire rigidly and to insulate it from 
the. span wire, but also to employ devices 
for this purpose that shall be as small and 
sightly as possible. The simplest way tc 



TROLLEY LINE COiSrSTRUCTIO:N-. 



227 



support a trolley wire from a span wire is 
by means of a trolley ear or insulator. 
Such a form of ear or insulator is shown in 
Fig. 105. e^ e^ is a metal casting, called 

A B 






Pig. 105. — Straight-Line Suspension, and Trolley 
Ear and Insulator. 

the ear. It is furnished with a narrow 
edge 5, Sy having tips Avhich are bent and 
soldered over the trolley wire, which lies in 
a OToove extending; under the entire leng;th 
of the ear. f,f^ is the body of the suspen- 



228 



ELECTRIC STREET RAILWAYS. 



sion, having two flanges at its extremities 
as shown. The suspension span wire lies 
in these flanges and around the head of the 
insulator. The insulator is made in two 




Fig. 106. — Trolley Ear and Suspension. 

parts, A and £j shown separately above, 
A^ being an insulating cap and J^, an insu- 
lating cone. These two parts are screwed 
together and grip the body between them. 
Fig. 106 shows another form of street line 



TROLLEY LINE CONSTRUCTION. 229 

siispensioD and ear, differing from the 
former merely in details of construction. 
The outer iron cap G^ has the cover v^ 
screwed down upon it in such a manner as 
to enclose the insulating tube L This insu- 
lating tube encloses in its turn the bolt 
which is screwed into the ear. The sus- 




Fig. 107. — Double-Curve Suspension. 

pension span wire is gripped tightly be- 
tween the flanged projections/,/*, of the 
body and the outside of the iron cap c. 

A great variety of line suspensions are 
employed. Fig. 107 shows a common form 
called a douhle-ciirve suspension^ named 



230 ELECTRIC STREET RAILWAYS. 

from the two lugs of the hood or cover. 
On the insertion of this form of suspension, 
the span wire has to be cut and the two 
ends fastened into the rings 1% r. In other 
respects the suspension is practically the 
same as that shown in Fig. 106. The 




Fig. 108.— Single-Curve Suspension. 

double-curve suspension possesses the ad- 
vantage that all the tensions exerted upon 
it, with the exception of that produced by 
gravitation, are exerted in the horizontal 
plane; that is to say, the span wire pulls 
sideways upon it in almost the same plane as 
the tension of the trolley wire lengthways. 



TROLLEY LINE CONSTEUCTION. 231 

Another form of suspensioD, called the 
single'Ciirve suspension is shown in Fig. 
108. This suspension is introduced at 
curves in the track or line Avhere only a 




e 

Fig. 109.— Bracket Suspension Eae . 

single pull is exerted on the trolley wire, 
instead of requiring a span. 

A form of hrachet suspension em% is 
shown in Fig. 109. Here the cylinder (7, 



232 ELECTRIC STREET RAILWAYS. 

is clamped firmly by the screw clamp P^ 
upon a bracket arm, while from the 
cylinder is supported the insulator I^ and 
ear e e^ upon the bolt h h. 

When two lengths of trolley wire have 
to be connected together, the connection is 
always made at an ear, or point of support. 




Fig. 110.— Splicing Ear. 

Such an ear is for this reason called a 
splicing ear. A form of splicing ear is 
shown in Fig. 110. The two ends to be 
connected are brouglit respectively to the 
ear at w and w\ under the grooves to x and 
x\ and then through the holes in the ear at 
the openings o and o. The wires are 
then soldered in at v)^ x and o. The 



TROLLEY LINE CONSTRUCTION. 283 

ear is bolted to its supporting insulator 
at B. 

Instead of soldering the ends of tlie 
wire in a splicing ear they may be clamped 
iu a device called an automatic eai\ shoAvn 
in Fig 111. Here the two wires are laid 




Fig. 111.— Automatic or Clamp-Splicing Ear. 

in the Jaws of the clamp at C^ O. The 
Jaws are then pressed together and secured 
by a bolt. 

The necessity for maintaining a taut 
trolley line, so as to ensure a good and 
continuous contact with the trolley wheel, 
requires that the line be ancliored about 



234 



ELECTRIC STREET RAILWAYS. 



every 1,000 feet. An anclior-strain ear 
is shown in Fig. 112. Strain wires are 




Fig. 112. — Anchor-Strain Ear. 

attached to the lugs a and h^ and are made 
fast, through insulators, to equidistant 
poles as shown in Fig. 113. The insula- 





FiG, 113.— Anchoring for Single and Double Track. 



TROLLEY LINE CONSTRUCTION. 235 

tors which are employed for this purpose 
are called strain insulators^ and are of 
various forms. K common form is shown 
in Fig;. 114. The two luo;s are cast into a 
spherical insulating mass. 




Fig. 114. — Strain Insulator. 

Trolley loire insulators have two func- 
tions to fill ; namely, a mechanical function ; 
^'. e,^ in providing an adequate support, 
and an electrical function ; ^. e,^ as an elec- 
trical insulator. In order to be sufficiently 
strong, suitable material must be employed 
and so arranged as safely to support the 
stresses exerted upon it. From an electri- 
cal point of view, the insulation afforded 
by an insulator is never that of the mater- 



236 ELECTKIC STREET RAILWAYS. 

ial of wliicli the insulator is formed, and 
is alwaySj in practice^ the insulation of the 
surface. That is to say, the electric leak- 
age, which takes place through an insulator, 
is practically all over the surface of the 
insulator, scarcely any passing through the 
substance of which it is formed. The con- 
dition of the surface, therefore, greatly 
affects the efficient action of the insulators ; 
for, if dirty or dusty, a thin film of moist- 
ure will entail a considerable electric 
leakage. Assuming the same surface con- 
ditions, a spherical insulator, such as that 
shown in Fig 114, would permit consider- 
ably greater leakage than a cup insulator 
of the type shown in Fig. 106, especially 
in wet weather. The electric leakage, 
however, which can be permitted on a 
trolley system is far in excess of that 
which can be allowed on a telegraph or 
telephone circuit ; since, if the total line 



TROLLEY LIISTE CONSTRUCTION. 237 

leakage gave rise to a loss of activity 
amounting to 1 K W, which would represent 
a total leakage current of 2 amperes under 
a pressure of 500 volts, or a total insulation 
resistance of only 250 ohms; the cost of 
this would be one or two cents per hour. 
The insulation of trolley systems usually 
averages from 2,000 to 100,000 ohms to 
the mile according to the weather. 

When a trolley road branches, it is 
necessary to branch the trolley wire. 
This is accomplished with the aid of a 
device, called a trolley frog. Fig. 115, 
shows three forms of trolley frogs. At A^ 
is a V-frog^ or simple two-ioay frog^ in an 
inverted position, so as to show the guides. 
a, is a metallic guide on the side of the 
single track, and h and c^ are the two 
guides on the side where the road bifur- 
cates. When the car has to be driven, 



238 



ELECTRIC STREET RAILWAYS. 



say from a to J, the rails on the track are 
so switched as to carry the car in that 
direction, and the trolley follows from the 






Fig. 115. — Trolley Frogs. 



guide a^ to the guide h. During the pass- 
age from the guide a^ to guide h^ the trolley 
wheel will either maintain contact with 
the line through its metal frame, or may 



TROLLEY LINE COISTSTRUCTION. 



239 



make a momentary flash at the point of 
crossing. B^ shows an inverted vigliU 
liand frog and C an inverted left-Jiand 
frog. AVhere a line divides into three 
branches special frogs, called three-way 
frogSy have to be employed. 





Fig. 116.— Trolley Crossing. 

At the intersection of two streets Avhere 
trolley wires necessarily cross each otlier, 
the crossing is effected through the 
medium of a device similar to a frog, 
and called a trolley crossing. Forms of 



240 ELECTRIC STREET RAILWAYS. 

trolley crossings are sliown in Fig. 116. 
Ay is a right-angle crossing^ and J3, an 
acute-angle crossing. The trolley wires 
are soldered in the groove over the four 
guides, and as a result, the trolley wheel 
has to drop slightly at a crossing to pass 
beneath the guides. Special forms of 
crossings are employed when it is desired 
to insulate the two crossing trolley wires 
from eacli other. 

Trolley wires are made in all sizes from 
No. 4 A. W. G., with a diameter of 0.204", 
to 'No. 000 A. W. G., with a diameter of 
0.410". The commonest size is No. 0, 
of 0.3249" diameter. The material is 
usually hard-drawn copper, although 
alloys are occasionally used. A No. 0, 
hard-drawn copper wire will safely 
bear a tension of 2,500 lbs. weight, and 
usually breaks at a tension of 5^000 



TROLLEY LINE CONSTRUCTION. 241 

weight. A hard-drawn copper wire of 
this size has a resistance of, approximately, 
0.52 ohm at 60^ F., its resistance being 
about 2 1/2 per cent, in excess of the re- 
sistance of the same size wire in soft 
copper, whereas silicon-bronze wire has 
sometimes about 2 1/2 times the resist- 
ance of the same size of soft copper wire. 



CHAPTER X. 



TEACK COJSrSTRUCTIOK. 



It is frequently a matter of surprise 
that the installation of a trolley road is 
almost invariably attended by the recon- 
struction of the track. The necessity for 
this reconstruction is to be found in the 
fact that electric cars are much heavier 
than ordinary horse cars, and contain run- 
ning machinery which is liable to injury 
from excessive jolting. This liability to 
injury from a weak and inferior track is 
increased by the greater speed at which 
electric cars run. Mo]*eover, in a badly 
constructed track difficulty is experienced 
in maintaining an efficient running contact 

242 



TRACK CONSTRUCTION. 



243 



bet\veeu tlie trolley and the trolley wire. 
For these reasons the construction of the 
roadbed and track requires careful at- 
tention. * 

In cities more care and expense are 
naturally taken with both line and track 




Fig. 117. — Track Construction. 



construction than in the open country, but 
the tendency is towards the employment 
of a steel girder rail weighing 90 lbs. per 
yard. Tliese rails are laid directly on 
wooden sleepers to which they are spikedc 
This construction is shown in Fig. 117, 
where the girder rails R^ i?, are spiked to 



2U 



ELECTEIC STREET RAILWAYS. 



the sleeper S, Sy and are also bound to- 
gether by the tie rod T^ 1] the roadbed 
being paved in this case with Belgian 
blocks. The rails are laid with their ends 
close together, no difficulty having been 
experienced from expansion in summer 




Fig. 118.— Track and Sleepeks, Showing Method of 
Breaking Joints. 

time. It is common to break these joints 
so that the joints of the rails on one side 
of the track shall come opposite to the 
middle of the rail on the opposite side. 
This is represented in Fig. 118, where 
Jj Jy Jj and J'j J\ show the relative 
positions of the joints of each rail. The 



TRACK CONSTRUCTION. 245 

sleepers in tliis case are also so distributed 
as to be closer together near the joints, as 
sho\vn. f^ f^ is the fish-plate with twelve 
bolts which pass through the rail and are 
screwed up against a similar fish-plate on 
the other side of the rail. 

With the use of a ground return it is 
necessary to ensure as intimate a contact be- 
tween the rails as possible, so as to secure 
a continuous- metallic path and to lessen 
the resistance that would other^\ise be 
introduced into the circuit. Mere contact 
of the ends of the rails with their connect- 
ing fish-plates is not sufficient, since rust at 
this surface produces a very considerable 
resistance. In order to avoid this, various 
methods of honding the rails have been 
proposed. This is attempted in a variety 
of ways, but the object is always to secure 
a permanent metallic connection between 



246 



ELECTRIC STREET RAILWAYS. 



successive rails. One of these rail bonds 
is represented in Fig. 119. To use this 
bond the rails are drilled close to the fish- 
plate and a bent copper rod of the shape 
shown at A^ has its two ends pressed into 
the holes, one end in each rail. A section 




Fig. 119. — Chicago Rail Bond. 



of the rail with the end of the copper rod 
projecting through it is shown at a. The 
plug Bj is then driven with the hammer 
into the opening of the rod so as to wedge 
it tightly into the iron rail. A cross-section 
of the rail, rod and plug is shown at C. 



TKACK CONSTRUCTION. 



247 



A somewliat similar method of effecting 
a rail bond consists in the use of stout 
copper wire in place of the copper rod. 
Here the ^vire is passed twice through 
holes in the rail each side of the fish plates 
and copper wedges are driven in so as 



n 




Fig. 120.— Wike Rail Bond. 

completely to wedge the wire against the 
metal rail. At intervals this wire is 
led directly across the track and enters 
into a bond with the other rail, thus effec- 
tively connecting the two rails together. 
A wire bond of this character is shown in 
Fi^. 120. 



248 ELECTKIC STREET RAILWAYS. 

The most efficient bond from a purely 
electric point of view is the id elded rail 
hand obtained by welding the rails together. 
For this purpose a very powerful electric 
current is passed through the ends of the 
rails, and pieces of iron, called chucks, 
which are used in place of the fish-plates. 
When completed, this joint is as solid and 
strong as the rest of the rails, thus aiford- 
ing a practically continuous iron rail, and 
therefore a continuous return circuit. 
Another method of accomplishing the 
same result consists in pouring melted cast 
iron around the ends of the rails after 
cleaning them, and so effecting a solid 
joint. Although success has not yet been 
perfectly obtained with continuous rails, 
yet it would appear that the stresses pro- 
duced by expansion and contraction in a 
uniform continuous rail are well within the 
limits of the elasticity of the steel. 



CHAPTEE XL 



ELECTROLYSIS. 



When an electric current is sent throug;!] 
a vessel containing ordinary tap water, the 
passage of the cuiTent is attended with the 
decomposition^ of the water into its con- 
stituent elements, oxygen and hydrogen. 
These elements are liberated, in the gaseous 
state, only at the points of entrance and 
exit of the current from the w^ater, the 
hydrogen being liberated where the cur- 
rent leaves the water, and the oxygen 
Avhere the current enters the water. If 
the conducting surface at which the cur- 
rent enters is oxidizable like iron, copper, 
lead, zinc, and nearly all ordinary metals 

249 



250 ELECTRIC STREET RAILWAYS. 

it becomes corroded or oxidized^ while a 
similar metal surface or electrode provided 
for the exit of the current from the water 
is unaffected^ the hydrogen being usually 
disengaged in bubbles. Decomposition 
effected in this manner, by an electric cur- 
rent, is called electrolytic decomposition^ and 
the corrosion of metals in liquids in this 
manner is called electrolytic corrosion. 

The earth or ground is only capable of 
acting as a return circuit by virtue of the 
moisture which is practically always pres- 
ent. Consequently, in all cases where the 
ground-return circuit is used, the metallic 
surfaces by which the current enters and 
leaves the ground are liable to electrolytic 
action. Where the current leaves the 
metallic conductors to enter the ground, or 
the moisture ^vithin the ground, there will 
be electrolytic corrosion, but where the 



ELECTROLYSIS. 



251 



current enters a metallic conductor on 
leaving the ground there will be no 
electrolytic corrosion, although there may 
be a liberation of hydrogen. On the con- 
trary, there will be an electi'ic protec- 
tion afforded the metal, at such points — the 




'p^^^^^ 






Fig. 121.— Simple Trolley Circuit. 

oxidation being less than that of similar 
metal, exposed to ordinary conditions in 
the absence of electric currents. 

The simplest condition of a trolley sys- 
tem is represented in Fig. 121. Here the 



252 ELECTKIC STREET RAILWAYS. 

generator G^ lias its positive pole con« 
nected to the trolle}^, that is^ the current 
enters the trolley from the generator, passes 
through the car motors, and returns to the 
generator, partly by the track and partly 
by the ground ; i. ^., the water in the 
ground, as a supplementary or auxiliary 
conductor. If the track had no electric 
resistance, or conducted perfectly, all the 
current would return through the track 
and none would pass through the ground. 
If, on the other hand, the track w^ere dis- 
connected at some point, for instance at 
each rail joint, then its resistance would be 
indefinitely great and practically all the 
current would pass through the ground. 

The better the electric conditions of the 
rail bonds, and the lower the resistance of 
the track, the greater will be the pro- 
portion of the current which will pass 



ELECTROLYSIS. 253 

turougli the track and tlie less the propor- 
tion which will pass through the diii'iised 
circuits in the ojround. Where the current 
leaves the rails on the track, to enter the 
ground, there will be corrosion or oxidation 
of those rails, but where the current re- 
turns from the ground to the track, or other 
buried metal at the power house connected 
with the generator, there will be no corro- 
sion, and even a tendency to prevent corro- 
sion. 

When electrolytic corrosion takes place 
the amount is perfectly definite. One 
coulomb of electricity passing through 
water will dissolve 0.000,002361 lb. of 
lead electrode, and 0.000,000,6393 lb. of 
iron electrode. Since an ampere is a rate 
of flow' of one coulomb-per-second, a cur^ 
rent strength of one ampere will dissolve 
0.000,002361 lb. of lead per second, or 



S54 ELECTRIC STREET RAILWAYS. 

0.000,000,6393 lb. of iron per second, and 
therefore, if an ampere be steadily main- 
tained for one year it will dissolve by cor- 
rosion 74.46 lbs. of lead and 20.16 lbs. of 
iron. If the current be increased to ten 
amperes, the amount of lead or iron cor- 
roded will be ten times as great, the chemi- 
cal action being directly proportional to 
the quantity of electricity which is passed. 

In the case of Fig. 121, corrosion will 
occur over the surface of the track where 
it lies in contact with moist eai'th. The 
corrosion will not be uniform, but will 
proceed faster at some points than others, 
the rate of corrosion depending upon the 
distribution of current over its surface ; i, 6"., 
on the local facility w^ith which the current 
escapes into the earth. The total amount 
of electrolytic corrosion will depend only 
on the total quantity of electricity, in 



ELECTROLYSIS. 255 

ampere-lioiirs or coulombs passing from 
the metal. 

If, liowever, the generator has its nega- 
tive pole connected to the trolley wire, 
and its positive pole connected to the 
track, the electrolytic conditions will be 
reversed ; for, the current will now leave 
the metallic surfaces for the moist ground 
in the vicinity of the power house, and 
there the corrosion Avill take place to an 
aggregate amount depending entirely 
upon the total quantity of electricity pass- 
ing into the ground. There will now be 
no corrosion where the current re-enters the 
track. 

Were the corrosion which occurs with 
street car systems limited to the track, the 
consequences would not be so serious, but 
in cities the corrosion affects the metallic 



256 



ELECTRIC STREET RAILWAYS. 



masses of the gas and water pipes, and 
their corrosion may lead to serious damage. 
Fig. 122 diagrammatically represents a 
street car system in which the positive pole 
of the generator is connected to the trolley, 
and the negative pole to the track. This 



DDDOa 



I 



^... w 



W 



w 



Fig. 122.— Diagram of Trolley System in Neighbor- 
hood OF Buried Pipe. Negative Pole Grounded. 



case differs from that of Fig. 121, only in 
the fact that a system of water pipes, W, 
W, is snpposed to lie in the vicinity of the 
track. If we snppose that a current of 
],000 amperes is steadily flowing from the 
generator through the car motors. 500 



ELECTROLYSIS. 257 

amperes or half the current may retui^u 
directly to the generator through the 
bonded track, 100 amperes may return 
through the ground, esca23ing from the 
track at more distant points and returning 
to it in the neighborhood of the station, 
while the baLance, or 400 amperes, may find 
its way into the good conducting path pre- 
sented by the system of water pipes, enter- 
ing it in the distant areas and leaving it in 
the vicinity of the power house. 

Under the circumstances above men- 
tioned, there will be electrolytic action at 
Ay where the current leaves the track, and 
at ^, \vliere it leaves the water pipe. The 
area of B, ^v ill be a comparatively narrow 
one, and, consequently, the rapidity of cor- 
rosion, will be comparatively great, since 
400 amperes maintained day and night, 
represents a total corrosion of roughly 



258 ELECTRIC STREET RAILWAYS. 

8,000 pounds per annum spread over a 
comparatively small area. If we connect 
the water pipe system with tlie generator's 
grounded terminal, as shown by the dotted 
lines, we reduce the quantity of electricity 
which leaves the surface of B, through the 
ground, since it will largely pass directly 
througli the new connection. By this 
means the electrolytic corrosion of the 
water pipes will be diministed. 

If the negative pole of the generator be 
connected to the trolley and the positive 
pole be connected with the track, as shown 
in Fig. 123, then, all other things remaining 
the same, there w^ill be corrosion at A 
and B / namely, at the portions of the water 
pipe remote from the power house and 
at the portions of the track near it. In 
this case, however, the area of w^ater pipe 
over which the corrosion takes place is 



ELECTROLYSIS. 



259 



more extended, and, consequently, the 
amount of corrosion on any one length of 
pipe in the district will be correspondingly 
less. 



QQQDQ 



ifr 



3e 



^ 



iur * - '^o-^ _ - - -^n TBI I 

iiii ^^gp. t t 1 t t t 

ir 



"w" 



Fig. 123.— DIAGRA.M of Tkolley System in Neighboii- 
HOOD OF Buried Pipe. Positive Pole Grounded. 



There are, therefore, two methods of 
dealing with the dangerous influences of 
electrolytic corrosion upon neighboring 
metallic pipes. The first is to ground the 
positive pole of the generator or generators 
at the power house, and so spread the cor- 
rosion over a large area of pipe distant 



260 ELECTRIC STREET RAILWAYS. 

from tlie power house, trusting to tlie en- 
larged area and the slowness of corrosion 
to avoid serious effects. In this case there 
is no advantage to be gained, so far as 
avoiding corrosion is concerned, by directly 
connecting the water pipe system with the 
grounded generator terminal. In fact 
there w^ill be an advantage in avoiding 
such connections. Tlie second method is 
to ground the negative pole of the gener- 
ator at the power house, as in Fig. 122, so 
as to bring the area of corrosive action 
within the neighborhood of the power 
house. If this course be adopted it be- 
comes important to protect this area by 
not only connecting the pipes witli the 
grounded generator terminal, but also by 
securing good electric connections between 
the track and the grounded terminal of the 
generator through bonding and ground 
feeders. 



ELECTROLYSIS. 261 

Wliichever method be adopted the use 
of ground feeders, rail weldiug, and effi- 
cient bonding necessarily reduces the 
danger of corrosion by offering a better 




Fig. 124.— Iron Pipe Corroded by Electrolysis. 

metallic conducting path to the return 
current. Fig. 124 represents a piece of 
pipe destroyed by the influences of electro- 
lytic corrosion. 



CHAPTEE XII. 



SWITCHBOARDS. 



If we trace the trolley wires of any 
street car railway system we will find 
them to form an interconnected network 
maintained at, approximately, 500 volts 
pressure relatively to the track. From 
this networl^ the feeders pass to the power 
house, either suspended overhead on poles 
and insulators, or underground through 
lead covered cables placed in suitable con- 
duits. Tracino; these feeders to their 
origin we will find them terminatiug at 
what is called the switcJiboard, The use of 
the switchboard is to enable the attendant 
at the power house to learn at a glance the 

262 



SWITCHBOARDS. 263 

electric condition of the system, and also to 
enable him to control or modify the electric 
condition Avith swiftness and convenience. 
To this end the switchboard is provided 
with a number of electric measuring in- 
struments, called respectively voltmeters^ 
for measuring the electric pressure in volts, 
and ammeters^ for measuring the electric 
current in the various circuits in amperes. 

Fig. 125, -shows a form of railroad 
sioitcliboard intended for use with three 
separate dynamo generators and three 
separate feeders. This switchboard con- 
sists of seven vertical panels formed of 
marble, a good insulator. The three 
panels on the right hand 'dve feeder panels^ 
and a generator is connected to and con- 
trolled by each. The central panel is a 
total-current and pressure panel^ for measur- 
ing the entire current supplied to the three 



364 EL'ECTRTC STREET RAILWAYS. 




Fig. 125.— Switchboard for Railway Power House. 



SWITCHBOARDS. 265 

feeder panels, and the main pressure of 
the power house. S, S, jSj are the three 
generator switcliss^ consisting each of three 
metallic knife blades maintaining connec- 
tion between metallic clips. In the posi- 
tion shown, all three switches are closed 
and all three generators are at work to- 
gether. Beneath the generator switches 
are rheostat hoxes^ H^ M^ M^ for control- 
ling the current supplied by each respective 
generator. A^^A, A^ are automatic circuit' 
hreakerSy which are so arranged that the 
current, supplied by their respective gener- 
ators, passes through stout coils or si^irals 
of copper rod, so that when this cuiTcnt 
strength becomes dangerously great, indi- 
cating an overload upon the generator, the 
magnetic action of the spirals releases a 
lever, which under the action of the spring 
flies back and breaks the circuit. M, M, M^ 
are three ammeters, each in circuit with its 



266 ELECTRIC STREET RAILWAYS. 

respective generator, so that the pointer 
or index shows at a glance the current 
strength and, therefore, the load upon that 
generator. Z, X, Z, are lightning arres- 
tors, intended to carry to ground any 
discharges due to lightning, thus avoiding 
damage to the system. Turning to the 
feeder panels, Sy s, s, are the three feeder- 
switclies. On closing one of these switches 
the particular feeder which supplies it is 
connected with the generator or generators, 
which may be in use, so that if all three 
of the switches shown be opened, the 
the entire load will be taken off the gene- 
rators, even though these be maintained 
running, a, a, a, are automatic feeder cir- 
cuit-breaherSy similar in their action to 
those already alluded to at A, A, A, 
Z, Ij ly are lightning arresters, connected 
to each feeder, similar to those at X, X, L. 
N^ is the main ammeter, supplied by all 



SWITCHBOARDS. 267 

three generator ammeters, Mj M^ M^ to- 
gether, and supplying in its turn, the 
various feeders. V^ is the voltmeter 
showing the pressure between generator 
terminals at the station in volts. 

The automatic cut-outs A^ A, A^ and 
a^ a, a^ are constructed as shown on a 
larger scale in Fig. 126. The current sup- 
plied by the generator passes from the 
clip P^ with its attached carbon plate K^ 
across the metal frame of the switch H^ 
to the opposite metal clip P\, and its 
attached carbon plate iV, thence by the 
terminal A^ through the three turns of 
the metallic coil or spiral C^ to the terminal 
. B, from whence it passes to the line. On 
lifting the handle Hj into the position 
shown on the left hand, a metallic connec- 
tion is established between the clips, and 
the switch is kept in position by a detent. 



268 



ELECTRIC STREET RAILWAYS. 



The current passing through the three 
turns of the coil C^ magnetizes them and 
tends to lift the iron core in its interior. 







^^'"'^^'^■^'■^^^■^i'^&SMMs^ 



Fig. 126. — Carbon-Plate Automatic Circuit-Breaker. 



As soon as the current strength exceeds a 
certain limiting safe value, the raising of 
the iron core by the increased magnetic 



SWITCHBOAKDS. 269 

attraction lifts the detent, and pei'mits the 
switch H^ to be thrown out of the clips 
into the position shown on the right hand 
side. As soon as connection at the clips 
P^ P\ is broken, a powerful arc would 
probably form w^hich might melt the 
switch. Contact is, however, maintained 
through the medium of the carbon 23lates 
N^ N^ and the carbon rods P^ JR^ whicli 
brush against them. The arc ^vhich takes 
place when thjs latter contact is broken is 
a carbon arc, instead of a copper arc, and 
such burning as does occur can only result 
in burning some of the carbon parts, which 
can be readily replaced from time to time. 

Another form of automatic circuit 
breaker is shown in Fig;. 127. Here the 
circuit is normally closed from the terminal 
R^ through the three turns of the spiral C^ 
the metallic projections j5, B^ and the 



270 



ELECTRIC STREET RAILWAYS. 



bridge of flexible copper strips t^ t^ between 
tliem. As soon as the current strength 
passing through the apparatus exceeds the 




Fig. 127. — Magnetic Circuit-Breaker. 



limiting amount for which it is set, the 
coil C\ attracts its armature against the 
tension of the spiral spring t^ and permits 



SWITCITBOAEDS. 271 

the larger spring S, to witlidraw the bridge 
t^ t, from the blocks £, B, A shunt cir- 
cuit, is. however, retained betAveen B^ B^ 
for a little Avhile after this contact is 
broken throuoh the two niao:net coils 
J/J Jf, and a smaller set of contacts in the 
upper part of the apparatus. The magnets 
become powerfully excited by the passage 
of the current through them and produce 
magnetic poles over the iron surfaces 
P^ P^ P^ and i^', one pole being, say north, 
and the other south. Between these pole 
pieces, the second or auxiliary contact' is 
broken by the descent of the lever ?, after 
the main contact is broken at B B^ and t. 
The arc, Avhich tends to follow the inter- 
ruption of the auxiliary contact, is instantly 
extinguished by the influence of the mag- 
netic flux between the polar projections, 
as already explained in the chapter on 
controllers. 



272 ELECTRIC STREET RAILWAYS. 

Should one of the generators, or one of 
the feeders, become overloaded, the auto- 
matic circuit-breaker will open its circuit 
and protect the generator placed therein. 
In many cases the overload may have been 
due to an accidental temporary short-cir- 
cuit, which almost immediately disappears. 
In such cases it is usual to reset the circuit- 
breaker by the use of the handle H^ until 
it is found that after three trials the appa- 
ratus refuses to remain set. It is then 
usual to allow the circuit to remain broken 
arid to search for the short-circuit. 

Fig. 128, shows a form of ammeter, such 
as is seen at M, M, M,\vl Fig. 125. Here 
the metallic pieces A^ B^ form the tei*mi- 
nals of the massive coil C^ liaving two 
turns placed directly in the circuit. The 
iron coi'e 0^ is attracted towards this helix, 
by the electromagnetic action of the cur- 



SWITCHBOARDS. 



273 



rent, this attraction increasing witli the 
current strength. The core O^ is suspended 
from a short balance arm pivoted at v^ and 




Fig. 128.— Fokm of Ammeter. 

having a long pointer or index p^ moving 
over a scale. When the current is cut off. 
the counterpoise overweights the iron core, 
and the pointer moves into a position 



274 ELECTRIC STREET RAILWAYS. 

opposite to the zero point on the left hand 
of the scale. As the current strength 
through the coil (7, increases^ the magnetic 
pull tends to overcome the gravitational 
pull on the counterpoise, and the pointer 
moves further and further towards the 
right. 

A form of voltmeter, shown at V, in Fig. 
125, is represented on an enlarged scale in 
Fig, 129. The principle and action of the 
apparatus are similar to that of the amme- 
ter in the preceding figure. The principal 
difference, however, is in the winding of 
the coil C^ which, instead of consisting of 
but two turns carrying a powerful current, 
has very many turns carrying a feeble cur- 
rent. Resistances of insulated wire wound 
on frames H i?, are placed in circuit with 
the vertical coil C, and the terminals of the 
generator. The current strength passing 



SWITCHBOAKDS. 



275 



in this circuit will be determined by Ohm's 
law. For example, if the total resistance 
of the coil C^ and the two resistances R^ H, 




Fig. 129. — Voltmeter. 



is 5,500 ohms, and the pressure at the gen- 
erator terminals is 550 volts, then the cur- 
rent strength passing through the circuit 



276 ELECTRIC STREET RAILWAYS. 

will be — — ^ volts = — th ampere = 100 
5,500 10 ^ 

milliamperes. The counterpoise f^ is so ar- 
ranged that at this particular current tlie 
pointer^, stands vertical and indicates 550 
volts. Should the pressure lise 10 per 
cent., or to 605 volts, the current in the 
circuit of the coil C, would increase 10 per 
cent., and its increased magnetic attrac- 
tion on the iron core within it ^vould 
deflect the pointer to a position which 
is marked 605 volts on the scale. It is 
evident, therefore, that this voltmeter is 
essentially an ammeter with a high resist- 
ance in its circuit. 

The general connection which is effected 
by the switches on the switchboard, omit- 
ting all details of ammeters, voltmeters, 
cut-outs and lii>:htninc^arrestors, is diao;ram- 
matically represented in Fig. 130. Here 



SWITCHBOARDS. 



277 



two main ha?% or bus-bars, B Ij, B' B' — a 
contracti-on for omnibus barSy so called be- 




FiG. 130. — General Connection Between Generators 
AND Feeders at Power House. 

cause tliey receive tbe entire current from 
the generators, — are connected, one to the 
feeders and the other to the track, ground 



278 ELECTRIC STREET RAILWAYS. 

feeders, or ground connection. Between 
these bus-bars the station pressure of say 
550 volts is maintained. One or more of 
the generators G^^ G^^ G^^ are connected 
across the bus-bars according to the amount 
of load o\).\X\^ lines; i. e,^ according to the 
number of cars that are running, and the 
work they are doing. If only a few cars 
are on the line the current required will be 
small, the electi'ic activity small, and a 
single generator may be sufficient. Thus 
the switch S^^ may be closed, leaving G^^ to 
take the entire load. If more cars are run 
the total current strength supplied to the 
feeders may require the addition of a sec- 
ond generator G2J by bringing it up to 
speed and excitation and closing the switch 
S^j and so on for the other generators. 



CHAPTER XIII. 

GENERATOKS AXD POWER HOUSES. 

TuRXixa now" from the s\yitchboards to 
the generators which supply them^ we 
notice two distinct types ; namely, the helt- 
driven generator^ and the direct'driven 
generator; i. e., a generator directly con- 
pled to the driving engine. The modern 
tendency in large power houses is to em- 
ploy very large generators, of say 1,000 
HP each, and to connect these directly 
to a driving-engine. In some power 
houses, however, belt-driven generators 
are employed. The belt-driven generatoi's 
have usually four poles, and very rarely 
have less than this number. The large 

279 



280 ELECTRIC STREET RAILWAYS. 

direct-driven generators have usually more 
than four poles, since it is found more con- 
venient and economical to construct gener- 
ators of large output with a greater 
number of poles. Fig. 131 shows an 
example of a belt-driven generator of 500 
KW output. Fig. 132 shows a direct- 
driven generator. 

Turning to Fig. 131, N, S, JV, S, are the 
four magnet poles wound with coils of 
insulated wire. In nearly all cases rail- 
way generators are compourtd-vjowid ^' i. e,^ 
there are two windings on each coil, one 
of very stout conductor and of very few 
turns, connected directly in the armature 
circuit, the other of many turns of fine 
wire, connected in a shunt, or by-path 
around the armature. The object of com- 
pound winding is to maintain the pressure 
automatically constant at the brushes, or 



282 ELECTRIC STREET RAILWAYS. 

at the switchboard bus-bars, notwithstand- 
ing changes in the number of cars, or load. 

The armature A, revolves within the 
annular space provided between the four 
pole- pieces, and with it the commutator 
O, On the surface of this commutator 
four sets of collecting hrnslies H^ H^ are 
fixed on a frame, capable of slight adjust- 
ment in angular position by means of the 
wheel shown at the base of the pedestal. 
T^ is one of the main terminals, with 
which the brushes are connected. B^ is 
the driving belt. 

In Fig. 132, similar letters refer to 
similar parts. Here there are also four 
poles and four sets of brashes, capable of 
being rotated together within certain 
limits by the pi'ojecting handle. The 
engine E^ is coupled directly to the arma^ 



(-1 

p 

»— I 
CO 

I 

n 
> 
d 

2 

o 

> 
SI 



o 

I 

H 

O 

5d 




284 



ELECTRIC STREET RAILWAYS. 



ture shaft through powerful springs con- 
tained within the coupling K. F^ is a 
fly-wheel and F, a cluster of six incandes- 
cent lamps in series, called j^ilot lamps. 




Fig. 133. — Armature of Direct-Driven Generator. 

A particular armature intended for a 
direct-driven railroad generator is shown 
in Fio;. 133. Here the armature consists 



GENERATORS AND POWER HOUSES. 285 

of two distinct parts ; namely, a body or 
core of iron, and conducting wires. The 
core is laminated^ that is, formed of a 
number of thin, soft, sheet-iron discs, pro- 
vided with slots in their external edges, so 
that when assembled in the shape of a 
short cylinder, a number of longitudinal 
slots or grooves are provided for the recep- 
tion of the wires. Without considering 
the winding m detail, it will suffice to say 
that the conductors are laid in the slots 
S^ S, and are then connected to the 
separate bars or segments of the eoDtmU' 
tator (7, C\ C. Fig. 134, shows the opera- 
tion of winding another form of railway 
generator armature, with the wires W^ TF, 
passing through the slots of the iron arma- 
ture core A. In this case the commutator 
is not yet placed on the shaft. A com- 
pleted armature is, however, shown below 
at By with its commutator at C. 



286 ELECTRIC STREET RAILWAYS. 

During the revolution of the armature 
through the magnetic flux produced by 
the field magnets of the generator, 
E. M. Fs. are induced in the winding, and 
when their circuit is closed through the 
feeders produce currents in them. The 
value of the E„ M. F. developed by the 
armature during its rotation, depends 
upon the total amount of magnetic flux 
passing through the armature and its 
wires, the total number of wires wound 
over the surface of the armature in the 
various grooves, and the number of revo- 
lutions which the armature makes per 
minute ; i. e.^ its rotary speed. The cur- 
rent strength which a given armature can 
maintain steadily, depends upon the size 
of the wires ; i. e.^ upon the resistance of 
the armature and its capability of readily 
disengaging the heat developed by the 
current in that resistance. The limiting 



288 ELECTRIC STREET RAILWAYS. 

current strengtli is usually determined in 
practice by tlie heating of the armature, 
which in good practice does not exceed 
40"" C. above the surrounding air, during 
continuous running. 

Illustrations of generator rooms ir 
power-houses, employing respectively the 
belt-driven and direct-driven types, are 
shown in Figs. 135 and 186. Fig. 135 
shows the interior of the Fifty-second 
Street power house of the Brooklyn street 
railway system, containing twelve belt- 
d liven generators, each of 500 KW ca- 
pacity, capable of a total output of 
6,000 KW, and representing 12,000 am- 
peres at 500 volts; or, approximately, 
11,000 amperes at 550 volts. These gen- 
erators are, however, capable of standing 
a considerable overload for a limited time. 
The switchboard S, is seen on a galleiy 
at the end of the room. 



3 



o 
o 



I— I 
O 

bj 

O 
O 

1^ 



O 

32 



o 

GC 
O 




^-^J^^^U^ 



^"^ 



C/i 



W&^^^^^^^^MU^^- fl 







290 ELECTRIC STREET RAILWAYS. 

A view of the interior of anotJier Brook- 
lyn railway power house ; namely, that at 
Kent Avenue, is shown in Fig. 136. Here, 
instead of being placed on the floor beneath 
the generators and connected to the latter 
by belts, as in Fig. 135, the engines are 
mounted side by side with the generators 
and directly coupled to the armatures. 
There are four large generating units in 
the room of the type shown at 1, 2, 3 and 
4 respectively. Each generator has twelve 
magnet poles, between ^vhich revolves the 
armature A, with its commutator C, at a 
speed of 75 revohitions per minute. The 
armature is driven by a double engine 
£J, E, The engine is a double, horizontal, 
compound-condensing engine, the generator 
being placed between the two halves. 
F^ jP, is the .engine fly-wheel placed on 
the main shaft, close to the armature. 
Each of these lai'ge generators has a 



5 



o 
o 






a 

O 

IS 
JO 

OQ 

H 
> 

o 

!21 




292 ELECTRIC STREET RAILWAYS. 

capacity of 3,000 amperes at a pressure of 
550 volts, representing an activity at full 
load of lj650 KW, and a total output, 
w^lien all are at full load, of 6,600 KW, or 
8,800 HP, approximately. The switch- 
board /Sy is seen at the end of the room 
through the fly-wheels of the two engines, 
on the left hand side of the figure. One 
of the generators in the figure; namely. 
No. 3, is shown incomplete, the field mag- 
nets being not yet assembled. The most 
recent development in street railway 
practice is in the direction of powerful 
slow-speed engines and direct-connected 
generators of this type. 

Fig. 137, shows a plan view of the 
engine and generator room in the Delaware 
Avenue railway power house at Phila- 
delphia. Here the general plan of engines 
and generators is similar to that shown in 



M 






Q 






d 

d 
c 

H 

> 
H 

O 




294 ELECTRIC STREET RAILWAYS. 

Fig. 136. There are four generating units 
marked 1, 2, 3, 4, each consisting of a 
1,650 KW, 12-pole generator, with its 
armature keyed to the shaft of a large 
compound-condensing engine of 2,000 HP 
(about 1,500 KW), arranged in two parts, 
one part on each side of the generator. 
S, S^ is the switchboard, behind ^vhich the 
feeders are seen. JP, is the air-pump con- 
nected with all the engines, and 5, is a 
small 300-KW direct-driven unit for light 
loads. One of the larger generator units 
is said to have operated as many as 212 
cars at one time. If working at full load 
this represents a mean activity of 8 KW 
per car. At this rate all four units could 
operate 850 cars. Each generator will 
stand the application of full load without 
any change in the position of its brushes, 
and will stand an overload of 50 per cent, 
with a slight movement of the same. 



296 ELECTKIC STKEET RAILWAYS. 

Fig. 138 shows a section of the power 
house represented in plan in Fig. 137. 
Here E^ E^ shows one of the engines, and 
g^ g^ one of the large generators on the 
lower floor. On the floor above are 
placed the boilers in two rows, one on 
each side, with an auxiliary G^ G^ between 
their fronts. The boiler accommodation 
is for ten batteries, each of 500 HP, repre- 
senting an aggregate capacity of 5,000 HP 
nominally. B^ B^ are the boilers, shown 
in cross-section on theriocht hand and inside 
view on the left. The steam pipes de- 
scend to the ceiling of the generator room, 
and the engine exhausts are led to the 
cellar where they are dripped, and the main 
exhaust pipe JT, X^ is led to the roof. 



CHAPTER XIV. 

OPERATION A:r^D MAIlSTTEISrANCE. 

The amount of power whicli a street 
car requires, depends, as ^ve have seen, 
upon its size, weight, the number of pas- 
sengers it is carrying, its speed, and the 
gradient on which it runs. It may vary 
from no power, when running down hill, 
to 100 KW when climbing a steep hill. 
It is often a matter of surprise to those 
who have been accustomed to see a pair of 
horses pull a street car through the city 
streets, tliat power, representing say more 
than 100 horses acting together, may be 
needed on occasions to propel electric 
cars. The reasons, however, are very 

297 



298 ELECTRIC STREET RAILWAYS. 

clear. An electric car weighs from 15,000 
to 20,000 pounds without passengers, 
while a horse car weighs only about 5,000 
pounds without passengers. The electric 
car will carry many more passengers than 
a street car, runs at a greater speed, and 
will climb grades impossible to be sur- 
mounted by two horses. 

A good rule to remember is that on the 
average, over a city street railroad system, 
an electric street car takes 1 KW for every 
mile per hour it averages, that is to 
say, if a car runs at 8 miles per hour 
it absorbs roughly 8 KW of electric 
power ; or, in 1 hour, would absorb a 
total amount of work equal to 8 kilowatt- 
hours. This rough estimate is, of course, 
independent of the power required to 
heat the car when electric heating is em 
ployed. 



OPEKATIOIS- AKD MAHSTTENAISTCE. 299 

The output of a station, that is, the load 
on the generators, varies markedly at 
different hours of the day. As a rule the 
heaviest load occurs in the mornino; and 
eveninoi: hours. The reason for the in- 
creased load is not only because a greater 
number of cars are running and the cars 
are more heavily laden, but the startings, 
which require considerable power, occur 
more frequently during the time of greatest 
load. Fig. 139 shows load diagrams taken 
in Boston, Mass., on June 16-19, 1895. 
It will be observed that the load varies 
from practically at 4 a. ]\r., to 12,000 
amperes and 800 cars, and that the total 
activity correspondingly varies from nearly 
to about 6,000 kilowatts. 

It has been found from a report in 1894, 
of 232 American electric street railwaj's, 
operating 5,120 miles of track with a total 



300 



ELECTRIC STREET RAILWAYS. 



capital of $316,700,000, and a funded debt 
of 1279,000,000, that the operating ex- 



15000 
14000 
"tolSOOO 
g 12000 
H 11000 
trlOOOO 
I 9000 
^ 8C00 
•S 7000 
I GOOO 

a. 5000 

S 

< ^000 

_) 

^ 3000 

H 2000 

1000 



800 

I 700 

O 600 
u. 

° 500 

<r 

ca 4C0 

2 

5 300 



^i 



12 3 4 5 



/ 



AMPERES (all STAT 



SUN JUNE 7 5, '189 



7 8 9 10 U 12 1 2 3 '; 
P.M. 



ONS) 



m 



7 8 iJ 10 11 12 



A.M. 

Fig. 139.— Load Diagrams at Boston, June 16-19, 1895. 

penses were 62.8 per cent, of the gross 
receipts, and the fixed charges 22.9 per 



OPERATION ATTD MAINTENAlSrCE. 301 

cent, leaving a net income of 14.3 per 
cent, of the gross receipts. 

The power required to be installed at 
the power house varies with a number of 
local conditions, but averages 20 KW per 
car in use. The cost of installino; this 
power is about $70 per KW for steam 
plants, including engines and boilers, and 
about $30 per KW of combined steam and 
electric plant,^or $100 per KW of total 
machinery. The cost of the electric 
equipment of a car, including two 25 HP 
motors and controllers, is about $1,000, and 
the cost of a car so equipped complete, 
roughly $2,300. The line construction 
costs roughly $5,000 per mile of double 
track, excluding track construction, but 
varies considerably, under different condi- 
tions. The total expense of a car mile^ 
i, €.^ a run of one mile per car, varies of 



302 ELECTRIC STREET RAILWAYS. 

course considerably with the size, the kind 
of system and the nature of the traffic, but 
a fair average may be considered as being 
from 15 to 25 cents per car mile. Of this 
the cost of supplying electric power is usu- 
ally only from 1 cent to 2 cents per car 
mile. In small systems all these costs are 
likely to exceed those given. 

The size and style of the car which is 
adopted, varies with the nature of the 
ti'affic, and the speed at which the car is 
expected to run. Under some conditions 
heavy cars running slowly are desirable, 
while in others light, high-speed cars are 
prefei'able. 

The population per mile of street rail- 
way track in the United States is, approxi- 
mately, 4,600, varying between 3,000 in 
the New England States, and 10,000 in the 



OPERATIOlSr AND MAINTENANCE. 303 

Southern States. In Canada, it is about 
11,600. The total street car mileage in 
the United States is about 6 per cent, of 
the total steam railroad mileage, and the 
gross earnings about 50 per cent, of the 
total passenger steam railroad earnings. 

For the purpose of facilitating repairs 
on the line, special wagons dra\Ani by 
horses are employed, called toioer ivagonSj 
arrang:ed so as to brino; the workmen 

O — o 

within easy access of the trolley wire. 
These wagons carry a light platform, 
which is either rigid or is capable of being 
raised and lowered. Both the frame of this 
wagon and its tower being of wood, the 
men working upon it are practically insu- 
lated, except in wet weather. 

In latitudes where snow falls the track 
is kept clear by an electric snoio sioeeper. 



304 



ELECTIUC STKEET KAILWAYS. 



One of these snow sweepers is shown in 
Fig. 140, where the track has been swept by 
the rotation of the brashes of the car. 
Fig. 141 shows one of these cars in action. 



^^:;v;'!' ■ , ^.. 








..■.---,'>^f>;S* 




s 


.--.--.. ,-./^,'- ;:,:,r 


a 


m 






~^^^ 

- - "^1^-^ % 







Fig. 140. — Electkic Snow Sweeper. 

There are four motors on one of these 
cars, usually of 25 HP each. Two of the 
motors are connected with the driving 
axles in the usual way, and the other two 



OPERATION AND MAINTENANCE. 305 

are wound for a higher speed and are con- 
nected so as to drive the revolving 




Fig. 141.— Snow Sweeper in Action. 



brushes. These sweeping brushes are 
fixed at an angle of 45° with the front of 
the car. 

The overhead trolley system has been 
objected to in cities on account of its 
unsightliness. The use of trolley poles 



306 ELECTRIC STREET RAILWAYS. 

with their span, guard, and trolley wires 
are certainly far from being a pleasing 
ornament to the streets of a well built city. 
For this reason attempts have been made 
to replace the overhead trolley system by 
an underground or conduit system of trol- 
leys, and also by storage-hattery propulsion. 
The overhead trolley system is, however, 
considerably more economical to erect and 
maintain than either a storage battery or 
conduit system. In large cities, where an 
increased cost is preferred to the unsightli- 
ness of the overhead trolley system, the 
underground trolley may find a successful 
use. It is already being tried in Washing- 
ton, D. C, and elsewhere in the United 
States, while in the city of Buda Pesth, 
Austria, an extended system of under- 
ground trolley roads has been running 
successfully for several years. 



CHAPTER XV, 

STOKAGE BATTERY SYSTEMS. 

The admitted unsightliness of the over- 
head trolley system and the difficulty of 
maintaining efficient operation of the 
undergrouncL trolley, under all conditions 
of climate, have led to many efforts to 
obtain a self-contained system of electric 
railways ; that is, a system in which each 
of the cars will carry its own electric 
driving power. In the early history of 
the art this was attempted by means of 
the primary battery. Primary batteries 
are now recognized as being altogether too 
expensive for this purpose, owing to the 
fact that they derive their motive power 

307 



308 ELECTRIC STREET RAILWAYS. 

from the consumption of zinc in a solution, 
a fact which will effectually prevent such 
batteries from competing with other types 
of motive power so long as the price of 
the zinc, and the solution in which it is 
dissolved, maintain anything like their 
present values. 

The nearest approach to the successful 
solution of the problem of an electrically 
propelled car, which carries its own stored 
electric energy, is found in the use of the 
secondary or storage cell. In this system 
the storage cells derive their charge, or 
stored electric energy, from electric cur- 
rent supplied to the cells at some central 
station. As some time is required to 
charge the cells, they are usually removed 
from the car to receive their charge. 
Before proceeding to the general descrip 
tion of the storage battery equipment of a 



STORAGE BATTERY SYSTEMS. 309 

car, a brief account of the construction and 
operation of storage batteries will be 
necessary. 

A great variety of forms have been 
given to the secondary or storage cell. In 
practically all cases, the material of which 
\\\%\v plates ox ele^nents 2iY% formed is lead. 
If two sheets of lead be immersed in a 
solution of dilute sulphuric acid, and an 
electric current be sent through the solu- 
tion from one plate to the other, an 
electrolytic decomposition will occur, 
whereby the positive plate^ or the plate at 
which the current enters, becomes oxi- 
dized, while the negative plate^ or that at 
which the current leaves the cell, liberates 
bubbles of hydrogen gas. During this 
process a C. E. M. F. is set up in the cell 
amounting, probably, to about 2.5 volts, 
and every coulomb, or ampere-second of 



310 ELECTRIC STREET RAILWAYS. 

electricity, which passes through the cell, 
does work in it amounting to 2.5 volt- 
coulombs or 2.5 Joules. At a rate of 1 
ampere, or 1 coulomb per second, the work 
so expended in the cell would amount in 
one hour, to 3,600 X 2.5 = 9,000 joules or 
2.5 %DaU-liouT8. 

If there were no resistance in the 
cell ; and if, moreover, no fi'ee hydi'ogen 
gas escaped from it, all the above 
work would be expended in chemical 
action, which would be stored up in the 
cell in the form of chemical products. So 
far as the C. E. M. F. is due to the drop 
of pressure through the resistance, the 
work is expended as heat, but so far as it 
is produced by the C. E. M. F. of chemi- 
cal action, it is theoretically possible to 
store the work in chemical combinations. 
If after having been charged in this way 



STOKAGE BATTERY SYSTEMS. 311 

the cell is removed from the charging 
circuit and its plates are connected 
thi'ongh a wire, it will act as a primar}^ 
battery ; that is to say the oxidized plate 
will behave like the copper plate of an 
ordinary bluestone cell, and the unoxidized 
plate like the zinc of such a cell. 

During; discharge, the E. M. F. of the cell 
may^ perhaps, average 2 volts, and each 
coulomb of electricity supplied through 
the circuit by this E. M. F. represents a 
delivery of 2 joules of Avork. During 
discharge, and the performance of work, 
the surface of the oxide on the posi- 
tive plate becomes partially deoxidized, 
while the plain lead or negative plate 
becomes partially oxidized. Finally, 
when the cell is completely discharged, 
the two plates are superficially the same, 
each being partially oxidized. A cell is, 



313 ELECTRIC STREET RAILWAYS. 

however, never permitted to completely 
discharge. In order to restore the cell to 
its active condition, it is necessary to once 
more charge it by passing through it the 
requisite quantity of electricity. 

In the case of a primary cell, in which 
the two plates or elements have essentially 
different chemical composition, the com- 
plete discharge is accompanied by the con- 
sumption of one of the plates; namely, 
the zinc plate. It is impossible, in prac- 
tice, to restore the active condition of the 
primary cell by sending a charging cur- 
rent through it, and the plates have to be 
renewed. In the secondary cell, instead 
of renewing the discharged plates, the 
electric current is permitted to reverse 
the chemical changes which have accom- 
panied discharge and thus restore the activ e 
condition. 



STORAGE BATTKUY SYSTEMS. 



313 



Instead of using plain lead plates, 
special forms of lead plates are employed 
to expose a very large surface to the 
active liquid. A form of storage cell is 




Fig. 142.— Form of Storage Cell. 



shown in Fig. 142. Here the glass cell or 
jar 6^ C^ contains seven flat plates, three 
of which are connected with the positive 
terminal P^ and four to the negative termi- 
nal N, The solution of sulphuric acid 



314 ELECTEIC STREET RAILWAYS. 

and water is poured in until the plates are 
covered. 



A positive plate is shown in Fig. 143. 
Here thirty-nine circular buttons, or discs 




Fig. 143.— Positive Plate. 



of peroxide of lead, are held tightly in a 
frame or grid of antimonous lead. The 
addition of antimony in sufficient quantity 
prevents the lead grid from being chemi- 



STORAGE BATTERY SYSTEMS. 



315 



cally attacked by the solution during 
cliar2:e or disc]iaro;e. Fig. 144 shows a 
negative plate, with sixty-four square 
buttons of soft porous or spongy lead 




Fig. 144.— Negative Plate, 

similarly held in an antimonous lead 
frame. The small holes in the centres 
of the buttons play no part in the action 
of the cell, and are made during the 
mechanical construction of the buttons. 



316 ELECTRIC STREET RAILWAYS. 

The principal difficulty which has been 
encountered with the use of storage cells 
in electric traction, has been in the electric 
overloads which have sometimes been 
necessary, and which greatly decrease the 
life of the plates. If the cars invariably 
ran upon a level grade and their load 
remained uniform, it would not be a diffi- 
cult matter to ensure an absence of electric 
overloads, or undue calls for power upon 
the batteries. In practice, however, owing 
to the existence of curves and grades 
and over-discharging, the cells are gener- 
ally soon injured, so that their mainten- 
ance becomes very expensive. Moreover, 
the great weight of the batteries adds 
largely to the non-paying weight of the 
car. Considerable improvements have, 
however, recently been effected in the 
storage battery whereby better results 
may be expected. 



STORAGE BATTERY SYSTEMS. 



317 



A form of storage battery car truck at 
present in use on Madison Avenue, New 
York City, is shown in Fig. 145. Here 
by turning the motors outwards towards 
the ends, that is supporting them on the 
opposite side of the axle to that usually 
adopted, the space A B C D/\^ reserved 




Fig. 145.— Storage Battery Truck. 

in the centre of the truck for the recep- 
tion of the storage battery. A truck with 
a storage battery in place is shown in Fig. 
146. In this truck sixty storage cells are 
arranged in two batteries of thirty cells 
each. Since the mean E. M. F. of dis- 
charge in a storage cell is, approximately, 



318 



ELECTRIC STREET RAILWAYS. 



2 volts, this represents a pair of batteries 
each having an E. M. F. of 60 volts. Each 
cell has 400 ampere-hours capacity; that 
is, is capable of supplying 40 amperes for 
10 hours, or 20 amperes for 20 hours, or 10 
amperes for 40 hours, etc., the total quan- 
tity of electricity being 400 X 3,600 = 




Fig. 146. — Car Truck with Batteries in Place. 

1,440,000 coulombs. The above men- 
tioned 1,440,000 coulombs, representing as 
they do the capacity of its battery, should, 
theoretically, be discharged whether the 
duration of discharge is long or short, that 
is to say, whether the cells are allowed 
to discharge in a few minutes or in many 
hours. 



STORAGE BATTERY SYSTEMS. 319 

In practice^ however, there is always 
a marked diminution in the avail- 
able quantity of electric discharge when 
the duration is too brief, say below three 
hours. If the E. M. F. of discharge aver- 
ages 2 volts, the total amount of energy 
available from each cell is 2 X 1,440,000 
= 2,880,000 coulomb-volts, or joules, and 
60 such cells should hold a total quantity 
of energy of 172,800,000 joules. Since 1 
watt-hour is 3,600 joules, and 1 KW hour 
3,600,000 joules, the total energy in the 
battery is 48 KW-hours. Consequently, 
the activity of the battery, assuming no 
loss, by very rapid discharging, would be 
8 KW maintained for six hours, or 12 
KW maintained for four hours. Of this 
power some will necessarily be lost in the 
motors and gears, so that, perhaps, only 
about 75 per cent, may be available at the 
car axles. 



320 



ELECTRIC STREET RAILWAYS. 



Fig. 147 shows diagrammatically the 
connections obtained in the different posi- 
tions of the controller of this car. In posi- 
tion 1, the two batteries are placed in 
parallel, making an effective E. M. F. of 60 



p¥l 


^ il 


mmnM 


4 


pl/l 


^ II 


><rj /s 


•2 


d -4' 




T 




T 




"T" 



Fig. 147. — Controller Positions. 

volts at main terminals, while the two 
motors are in series, each motor receiving 
30 volts. If under these conditions the 
activity of the battery is 12 KW, the cur- 
rent strength received by the two motors 
12,000 



in series will be 



60 



200 amperes. 



STORAGE BATTERY SYSTEMS. 321 

In the second position, a shunt is thrown 
around the field magnets of the motors, 
thereby diminishing their magnetic power, 
and requiring a greater speed from the 
armatures in order to develop the neces- 
sary C. E. M. F. of 60 volts in all. 

In the third position, the two batteries 
are thrown in series, representing a total 
E. M. F. available at terminals of 120 
volts, and a corresponding increase in the 
speed of the unshunted motors to produce 
this C. E. M. F. 

In the fourth position, a shunt is again 
thrown around the field magnets of the 
two motors, and their speed is correspond- 
ingly increased. 

In the fifth position, the two unshunted 
motors are thrown in parallel, instead of in 



322 ELECTRIC STREET RAILWAYS. 

series, thus calling upon eacli motor to de- 
velop a total C. E. M. F. of 120 volts.' 

In the sixth and last position, the mag- 
nets of the motors are shunted, requiring 
the armatures to run faster in order to pro- 
duce 120 volts total C. E. M. F. in the 
motor under these conditions. 

When the car returns to the car house 
and the battery has been sufficiently dis- 
charged, it is lifted bodily from the truck 
and replaced by a charged battery. 



CHAPTER XVI. 

ELECTRIC LOCOMOTIVES. 

Within large cities, municipal ordinances 
generally limit the speed of street cars to 
about eiglit miles per hour. In suburban 
districts, however, a speed is usually per- 
mitted as high as fifteen miles per hour^ 
while in inter-urban traffic, speeds of thirty 
miles per hour or more are sometimes 
reached. As the velocity of the cars in- 
crease, the electric activity which must be 
suj)plied to them increases in nearly the 
same proportion ; for, the torque exerted by 
the motors on a given gradient remains 
nearly the same at all the above men- 
tioned speeds, the rate only varying at 
which that torque is exerted. 

323 



324 ELECTRIC STREET RAILWAYS. 

At still higlier speeds tlian the preced- 
ing, the friction between axles and journals, 
and the wheels and the track, does not sen- 
sibly increase, but the friction between the 
surface of the car and the air does sensibly 
increase, so that, at speeds above 100 miles 
per hour, the track and journal friction 
would probably commence to be small 
compared with the resistance to air dis- 
placement and friction. Consequently, for 
very high speeds, the form of the moving 
car becomes nearly as important as the form 
of the hull of a steamer ; only in the case 
of the latter, the hull only is exposed to the 
friction against the water, while in the case 
of the car, the entire surface is moved 
through the air. 

The question has often arisen as to the 
early probability of replacing steam pro- 
pulsion on ordinary railroads by electric 



ELECTRIC LOCOMOTIVES. 325 

propulsion. The schedule speeds of ex- 
press trains on steam roads have altered but 
little during the last twenty years, Judg- 
ing from an inspection of railroad time 
tables included in that period. There is 
no doubt, however, that the introduction 
of the electric locomotive would permit 
much higher speeds to be safely attained, 
and, when this fact is taken in connection 
with the manifest advantages possessed by 
electric propulsion, it would seem that in 
electricity, steam has a formidable rival in 
this field. The question, however, is one of 
public demand, and economy of transpor- 
tation. There can be no doubt, that so far 
as regards economy in long-distance trans- 
portation, steam propulsion is cheaper than 
electric propulsion, owing to the cost of the 
plant, since the cost of transmitting powder 
electrically increases rapidly wath the dis- 
tance. Consequently, for freight and slow 



326 ELECTRIC STREET RAILWAYS. 

traffic, it does not seem tliat tlie immediate 
future will witness tlie displacement of the 
steam locomotive, but for high-speed pas- 
senger transportation, the extra cost of the 
electric equipment may be repaid by the 
increased economy in time of transit, so 
that it does not seem improbable that in 
the near future the high-speed passenger 
locomotive may come into use on railroads. 

As an example of experiments which 
have been tried in the dn^ection of high- 
speed electric railroads, Ave may mention 
the bicycle railroad shown in Fig. 148. 
Here the car runs on a single rail and rests 
on two Avheels, which, instead of being 
placed side by side, as in the ordinary 
truck, are in the same plane, like a bicycle, 
one being placed in the front and the other 
in the rear. The ends of the car are tap- 
ered, as shown. To prevent the car from 



^1 



o 

O 

> 






a 

> 

o 

K 




.:-ani'fe., _-iJ?x 



328 



ELECTRIC STREET BAILWAYS. 



falling sideways when at rest, it is sup- 
ported by guide wheels pressing upon the 
upper or guide rail, which serves the double 




Fig. 149. — Section of Bicycle Cab. 

purpose of a support and an electric 
conductor. A cross-section of a double 
deck car is shown in Fig. 149. It will be 
seen that these cars are only of half width, 



ELECTRIC LOCOMOTIVES. 329 

two being able to pass each, other with nine 
inches clearance within the space occupied 
by an ordinary 4' 8 1/2" track. The ad- 
Yantag:e claimed for this construction is 
that it not only enables the traffic to be 
doubled upon any existing railroad by 
erecting the upper or trolley guides, one 
for each existing rail, but it also enables 
the weight of the cars to be materially 
reduced, since the narrow car enables 
the necessary^ structural strength to be 
obtained Avith less material, and the 
weight of the loaded car, per passenger 
carried, would be about four times less than 
with the existing construction, thus econo- 
mizing in activity expended against journal 
friction and grades. The electric propul- 
sion is obtained from a single motor M^ in 
the front wheel of the car. On the track 
shown in the figure, speeds of 45 miles per 
hoiu^ are readily obtained, and speeds of 



330 ELECTRIC STREET RAILWAYS. 

over 60 miles an hour are claimed to have 
been reached on a track 1 1/2 miles in 
length. By giving a lean to the upper or 
guide rail no difficulty has been found in 
going around sharp curves, since no appre- 
ciable strain is produced. A disadvantage 
of the system is that it can only provide 
seats for tvro in the width of the car. 

Another purpose to which the electric 
locomotive has already been applied is to 
the drawing of trains" of cars through long 
tunnels on steam roads. As is well 
known considerable difficulty is experi- 
enced in ventilating long tunnels when 
steam locomotives pass through them fre- 
quently. This difficulty is entirely over- 
come by the use of the electric locomotive. 
Here the requirements are not for high 
speed, but for a powerful draw-bar pulL 
An example of this type of electric loco- 



ELECTRIC LOCOMOTIVES. 331 

motive is seen in the Belt Line Tunnel at 
Baltimore. This tunnel is about a mile 
and a half long, and has a gradient of 
about forty-two feet to the mile. Since 
the freight traffic is heavy, a powerful 
locomotive is required to draw the trains. 
Fig. 150 shows the entrance to the tunnel 
with the electric overhead conductors 6^ 
6^ in place. One of these conductors is 
provided for each of the two tracks, w^ 
Wj are the copper supply wares, and K^ K^ 
are the supporting catenaries or rod 
chains. 

Fig. 151 shows one of the conductor sup- 
ports from the catenary, r^ r, are the rods 
of the catenary. I^ is the conical insulator. 
i?, jS, the suspension rods from this insu- 
lator. B^ Bj is the beam supported by 
these rods, and Cj O^ the conductors which 
are formed of iron bars, arranged opposite 



332 ELECTEIC STREET RAILWAYS. 




Fig. 150.— The Entrance to the Tunnel. 



ELECTRIC LOCOMOTIVES. 



333 



eacli other^ so as to leave a slot between 
them and enclose an inverted condnit. In 
this conduit slides a brass shoe supported 




Fig. 151.— Overhead Conductor Support. 



on a flexible rod from the top of the loco- 
motive. TF, is a cross-section of the sup- 
ply wires or feeders, which are stranded 



334 ELECTRIC STREET RAILWAYS. 

copper cables about one incli in diameter 
clamped directly to the beam as shown. 

The method of supporting the conduct- 
ors in the tunnel is shown in Fig. 152. 
Here M^ M, M^ is the masonry arch of 
the top of the tunnel^ B^ B, are bolts let 




Fig. 152.— Method of Suppokting Conductors in the 

Tunnel. 

into the masonry, and supporting a chan- 
nel frame by two conical insulators % i, 
at the ends. Two other insulators i\ i\ 
support the conductors o, c. 

Fig. 153 shows the electric locomotive 
pulling a steam locomotive and train 
through the tunnel, i^ jF, is the flexible 



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336 ELECTRIC STREET RAILWAYS. 

conductor correspondirig to the trolley pole 
of an ordinary street car, and carrying at 
its extremity the shoe running in the con- 
ductor overhead. An end view of the 
locomotive is shown in Fig. 154. The 
trolley fastened to the top of the locomo- 
tive is shown in side and end view at Fig. 
155. Sy is the shoe, and J, J^ the joints in 
the structure, which automatically lengthen 
and shorten the trolley pole, to conform 
with the varying height of the trolley con- 
ductor. This locomotive weighs ninety- 
six short tons in all, and is supported on 
two trucks and four pairs of driving 
wheels. A motor is mounted directly 
on each driving axle, thus placing four 
motors in the locomotive. One of 
these motors is shown in Fig. 156. 
Here the iron-clad armature A^ A^ is 
mounted in a sextipolar field frame F^ F. 
These motors being mounted on the driv- 



ELECTRIC LOCOMOTIVES. 



33"/ 




Fig. 154. — End View of Electric Locomotive. 



338 



ELECTRIC STREET RAILWAYS. 



ing axles through special flexible connec- 
tions without the intervention of gears, are 
called g earless motors. The method of 
mounting them in the truck is shown in 




Fig. 155. — Side and End Views of Trolley. 



Fig. 157. Here S, S, is the side frame 
c7^ J, are the journal boxes of the two 
axles in the truck, and M, i/, the motors 
mounted flexibly over each axle. 



ELECTRIC LOCOMOTIVES. 



339 



The current is supplied to eacli motor 
armature through six pairs of carbon 




Fig. 156.— Motor of Electric Locomotive. 

brushes arranged around the periphery of 
the commutator. The total current sup- 
plied to each motor is normally about 500 



340 



ELECTRIC STREET RAILWAYS. 



amperes at full load. The pressure of sup 
ply is about 600 volts. The normal 
activity absorbed by eacli motor at full 
load is, therefore, 300 KW, or, roughly, 
about 400 HP. Since there are four 
motors, this powerful locomotive absorbs 




Fig. 157. — Truck, Showing Motors in Position. 

a total activity of about 1,600 HP, and 
the locomotive is rated at 1,500 HP. The 
locomotive is designed so as to exert a 
steady pull of 40,000 pounds, or 20 short 
tons, at the draw bar when drawing a train 
twelve miles per hour. This represents 
a useful activity of 1,280 HP in addition 



ELECTRIC LOCOMOTIVES. 



341 



to tliat required to move the locomotive 
itself. The maximum available draw-bar 
pull is stated to be 60,000 pounds. The 




Fig. 158.— '' Terrapin Back" Electric Mixing 
Locomotive. 



draw-bar pull in an electric locomotive is 
uniform, whereas the draw-bar pull in the 
steam locomotive is necessarily variable at 
different portions of the stroke. The 



342 ELECTRIC STREET RAILWAYS. 

draw-bar pull of a powerful 60 sliort- 
ton steam engine does not usually exceed 
25,000 pounds. 

The electric locomotive lias recently 
found a field of application in mining 
operations. It is especially fitted for such 
work from the ease with which it is con- 
trolled. Fig. 158 shows a form of mining 
locomotive suitable for hauling trains of 
trucks through the galleries of a mine. 
It will be noticed that the trolley pole is 
of the same general type as that described 
in connection wdth the locomotive of the 
Baltimore ' tunnel. 



CHAPTER XVII. 

ELECTRIC HIGH-SPEED RAILROAD SERVICE. 

It has recently been decided to equip 
the New York terminal section of tlie New 
York Central and Hudson River Railroad 
Company mtli electric traction for a dis- 
tance of 34 miles on the main line, all pas- 
senger traffic being handled in this manner 
south of Croton. 

The electric locomotives for this service 
are the largest yet consti^ucted, being of 
2,200 HP. nominal rating, and 2,870 HP. 
maximum output. They are designed to 
drive a 500-ton train at a speed of 60 
miles per hour. One of these locomotives 

343 



344 ELECTRIC STREET RAILWAYS. 

is shown in Fig. 159. It weighs 95 tons 
and is able to give a draw-bar pull of 17 
tons. This locomotive will take the place 
of a standard high-speed steam locomotive 
of 100 tons' weight and 14 tons' draw-bar 
pull, besides dispensing with a 60-ton coal 
tender. There are four motors in the loco- 
motive truck, each of 550 HP. nominal 
rating, and intended to take a maximum 
current of 1,075 amperes at 600 volts, pres- 
sure or 645 KW. of electric powxr. 

One of the motor armatures is shown in 
Fio;. 160, It will be seen that the arma- 
ture is built directly upon the axle, C be- 
ing the commutator, and A A the armature 
core, within the superficial slots of which 
the conductors are buried. 

Fig. 161 shows a longitudinal section of 
the locomotive with the four motors in the 



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346 ELECTRIC STEEET RAILWAYS. 

truck. The motors are bipolar^ and the 
field poles, instead of being curved concen- 
trically with the armature, are nearly flat ; 
so that the armatures can be removed from 
the poles without removing either poles or 




Fig. 160. — Motor Armature Mounted on Axle. 
driving wheels. This arrangement admits 
of ^reat range of vertical play to the arma- 
tures relatively to the field poles. 

The four motors are connected magneti- 
cally in series, the total magnetic flux pass- 



348 



ELECTRIC STREET RAILWAYS. 



ing in succession throngli "eight air-gaps. 
The main frame is of cast steel, providing 
the mametic circuit as well as the struc- 

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Locomotive under Test. 

The curve sheet of Fig. 162 is the record 
of the reported preliminary trial of the 
first of these locomotives, Avhen hauling a 
total train weight of 431 short tons. After 



IIIGU-SPEED RAILROAD SERVICE. 3-19 

120 seconds the speed of the train was, in 
this trialj nearly 40 miles per hour, repre- 
senting a steady acceleration of about 1-3 
mile-per-honr-per-second. The main-line 
starting current commenced at 800 am- 
peres with the motors all in series. The 
current was then shut off automatically 
at the controller upon changing to the 
parallel connection, some 23 seconds after 
starting. The current is shown to have 
then increased to 1,800 amperes, during 
several controller steps. Finally, after 40 
seconds, the cuttino; out of all resistance 
brought the supply current to 3,400 am- 
peres. The voltage dropped at this time, 
however, to 320 volts, owing to the load. 
The current steadily diminished after this 
until 280 seconds from the start, when 
three miles had been run, and the current 
was shut off* at the controller. The speed 
was then 63 miles per hour. 



350 ELECTRIC STREET RAILWAYS. 

The electric locomotive has certain dis- 
tinct advantages over a steam locomotive 
of equal power. 

(1) It is much cleaner. 

(2) It produces very little noise in oper- 
tion. 

(3) It is always ready for service. 

(4) It is relatively very steady and free 
from vibration in running. 

(5) It requires much less skill and vigi- 
lance to control. 

(6) Its draw-bar pull is also uniform 
at all positions of the driving Avheels. 

The power for driving these locomotives 
will be generated by steam turbines de- 
livering alternating current at 11,000 volts 
to high-tension feeders, from which direct- 
current power will be delivered to the 
third rail at intervals, through step-down 
transformers and rotary converters. 



INDEX. 

A 

Active Coil, 80. 

Coil, Deflection of, by Electromagnet, 85. 

Coil, Deflection of, by Horseshoe Magnet, 

84. __ 
Coil, Deflection of, by Opposite Magnet 

Poles, 83. 
Coil^ Deflection of, by Single Magnet Pole, 

82. 
Active Conductor, 80. 
Activity, International Unit of, 23. 

, Practical International Unit of, 24. 

, Unit of, 21. 

Acute-Angle Crossing, 240. 

Ammeter for Railway Generator Switchboard, 263. 

— for Railway Switchboard, 272 to 274. 

Ampere, 28. 

Analogy between Liquid and Electric Flow, 3 to 7« 

351 



352 INDEX. 

Anchored Filament for Electric Street Car Lamp, 

138. 
Anchor-Strain Ear, 234. 
Armature Coils of Car Motor, 72. 

Core, Lamination of, 74. 

Core, of Car Motor, 72. 

, Cylinder, 75. 

— Pinion, 115 to 117. 

, Ring, 75. 

Windings of Car Motor, 72. 

Arrester, Lightning, 201 to 203, 266. 
Automatic Car Switcli, 129. 

Circuit-Breaker, 265. 

Cut-Out, 198. 

Ear, 233. 

Feeder Circuit-Breaker, 266. 

Axle Gears, 116. 

B 

Back Electric Pressure, 47. 

• Water Pressure, 45. 

Bars of Commutator, 77. 
Base, Trolley, 205. 
Belt-Driven Generator, 297. 

Berlin Industrial Exhibition of '79, Electric Rail- 
way of, 12. 



INDEX. 353 

Bicycle Railroad, 326 to 330. 
Block, Fuse, 198. 
Blow-Out, Magnetic, 160. 
Bond, Welded Rail, 248. 
Bonding of Rails, 245, 246. 
Bonds, Rail, 246. 
Box, Sand, 131, 132. 
Boxes, Journal, 104. 

, Rheostat, 265. 

Bracket Pole for Double Track, 221. 

Support for Single Track, 222. 

Suspension Ear, 231. 

Suspension for Single Track, 223, 

Brackets, 219. 
Brake Handle, 122. 

Mechanism, 122. 

Shoes, 99. 

Breaker, Automatic Circuit, 265. 
Broken Circuit, 27. 
Bus-Bars, Generator, 278. 
By-Path or Shunt, 182. 



c 

Canopy Switch, 199, 200. 

Car Body, 97. 

Brake, Electric, 126 to 128. 



354 INDEX. 

Car Brake, Pneumatic, 122. 

Controller, Definition of, 155. 

Controller for Storage Battery System, 

320 to 322. 
Controller, Interior Construction of, 158, 

159. 
Controller, Method of Operation of, 162 to 

191. 

Heater, Heating Coils of, 144, 145. 

Heating, Temperature-Regulating Switch 

for, 147 to 151. 

— Lamp, 136, 137. 

— Lamps, Circuit of, 135. 

1 — Lamps, Efficiency of, 138. 

Lamps, Fixtures for, 139, 140. 

Mile, 301. 

Motor, Armature Core of, 72. 

Motor, Armature Windings of, 72. 

Motor, Commutator of, 72. 

Motors, Gear Wheels of, 69. 

Truck, 67, 68, 97. 

Trucks and Cars, 97 to 133. 

Trucks, Methods of Supporting, 97, 98. 

Trucks, Storage Battery, 317. 

Wheels, Closed, 110. 

Wheels, Gearing for, 113. 

Wheels, Open, 108. 



INDEX. 355 

Car Wheels, Skidding of, 129. 

Wheels, Tread of, 109. 

Cars and Car Trucks, 97 to 133. 

, Electric Lighting and Heating of, 134 to 

153. 
Carbon-Plate Automatic Circuit-Breaker, 267,268, 

269. 
Cell, Secondary, 309. 

— , Storage, 309. 

Chicago State Fair, Street Car Line of '84, 14. 

Rail Bond, 246. 

Circuit-Breaker, Carbon-Plate Automatic, 267, 

268. 269. 

Breaker, Magnetic, 269 to 272. 

• Breakers, Automatic Feeder, 266. 

, Broken, 27. 

, Closed, 27. 

, Electric, 27. 

, Hydraulic, 30, 31. 

, Made, 27. 

, Open, 27. 

or Line, Drop in, 54. 

Climbers, Pole, 224. 
Clamp, Splicing Ear, 233. 
Closed Car Wheels, 110. 

Circuit, 27. 

Coil, Active, 80. 



356 INDEX. 

Coils, Armature, of Car Motor, 12, 
Collecting Brushes of Generator, 282. 
Commutator of Car Motor, 72. 

of Generator, 285. 

Segments, 77. 

Strip, 77. 

Compound- Wound Generator, 280. 

Conductance, 40. 

Conducting Wires, Resistance of, to Electric 

Flow, 34. 
Conductor, Active, 80. 
Conductors, Feeding, 64. 
Conduit Trolley System, 306. 
Coney Island, Street Car Line of '84, 14. 
Consequent Magnet Poles, 90. 
Continuous Rail, 248. 
Controller, Diagram of Connections for First 

Working Notch, 164. 
Controllers and Switches, 154 to 203. 
Corrosion, Electrolytic, 250. 
Coulomb, 48. 
Counter-Electromotive Force, 45, 47. 

Electromotive Force of Rotation, 166. 

Electromotive Force of Self-induction, 165. 

Crossing, Right-Angle, 240. 

, Acute-Angle, 240. 

■ , Trolley, 239. 



INDEX. 357 



Curreiit, Electric, 28. 

, Electric, Unit of, 28. 

Currents, Eddy, 74. 
Cut-Oiit, 141. 

, Automatic, 198. 

Cylinder Armature, 75. 

D 

Davenport, 8. 

Davidson, 8. 

Decomposition, Electrolytic, 250* 

Diagram of Load, 299. 

Direct-Driven Generator, 279. 

Double-Curve Suspension, 229. 

Gear Wheels, 119. 

— Pinion, 119. 

Reduction Motors, 118. 

— Track Bracket Pole, 221. 

Truck, 99. 

Dr, Ohm, 35. 

Drop in Line or Circuit, 54. 

E 

E. M. R, 29. 

Ear, Anchor-Strain, 234. 
^ Automatic, 233. 



358 INDEX. 

Ear, Bracket-Suspension, 231. 

Clamp, Splicing, 233. 

, Splicing, 232. 

Eddy Currents, V4. 

Edison, 13. 

Efficiency of Car Lamps, 138. 

of Line Circuit, 59 to 63. 

of Motor or Generator, 57 to 59. 

of Motor or Generator, Effect of Load on, 

58, 59. 
Effective Pressure, 47. 
Eighth Working Notch, Diagram of Connections 

of, 188. 
Electric Car Brake, 126 to 128. 

Car Heaters, Advantages of, 143, 144. 

• Car, Weight of, 298. 

Circuit, 27. 

Current, 28. 

Current, Unit of, 28. 

Gradient, 46. 

Lighting and Heating of Cars, 134 to 153. 

■ Street Car Lines of the United States, 

Statistics of, 14. 

Locomotive, Motor of, 339. 

Locomotives, 323 to 342. 

Locomotives of the Baltimore Tunnel, 330, 

331. 



INDEX. 359 

Electric Locomotive, 343. 

Locomotive Armature, 346. 

Locomotive Performance, 348. 

Locomotive Advantages, 350. 

Mining Locomotive, 341. 

Motor, 67. 

Railroad System, Self-Contained, 307. 

Resistance, 34, 35. 

Snow-Sweeper, 303, 304. 

Electricity, Quantity of, 42. 
Electrolysis, 249 to 261. 
Electrolytic Corrosion, 250. 

Decomposition, 250. 

Electromagnetic Pull, 84. 

Twist, 84. 

Electromotive Force, 29. 
Elementary Electrical Principles, 16 to 66. 
Elements of Storage Cell, 309. 
Emergency Switch, 156. 

F 

Farmer, 10. 
Feeder Panels, 263. 

System, 65. 

Feeders, 64. 

Feeding Conductors, 64. 

Points, 65. 

Field, 13. 



360 IJSTDEX. 

Field Magnet Coils, Effect of Shunting, on Motor 
Speed, 183, 184. 

Filaments, Anchored, for Car Lamps, 138. 

, Non-Vibrating, for Car Lamps, 138. 

Fixtures for Car Lamps, 139, 140. 

Flattening of Wheels, 131. 

Flow, Electric, 28. 

, Electric and Liquid, Analogy between, 3 

to 7. 

Foot-Pound, 18. 

— ' Pound-per-Second, 21. 

Force, Counter- Watermotive, 45. 

, Counter-Electromotive, 47. 

, Electromotive, 29, 31. 

, Electromotive, Unit of, 32. 

Four-Pole Electric Motor, 88. 

Fourth Working Notch of Car Controller, Dia- 
gram of Connections of, 183. 

Frog, Left-Hand, 239. 

, Right-Hand, 239. 

.Three- Way, 239. 

, Two- Way, 237. 

Fuse Block, 198. 

, Safety, 198. 

G 

Gear Covers, 120. 

Wheel, Double, 119. 



INDEX. 361 

Gear Wheels of Car Motors, 69, 
Gears, Axle, 116. 
Gearing for Car Wheels, 113. 
Generator, Belt-Driven, 279. 

Bus-Bars, 278. 

, Collecting Brushes of, 282. 

, Commutator of, 285. 

, Compound-Wound, 280. 

, Direct-Driven, 279. 

, Efficiency of, 57 to 59. 

, Laminated Core of<, 285. 

Rooms of Power House, Illustrations of^ 

288 to 294. 

Switches, 265. 

Generators and Power House, 279 to 296. 
Gradient, Electric, 46. 

, Hydraulic, 44. 

Green, 11. 

Grid or Frame of Storage Cell, 314, 

Guard- Wire Span, 225. 

Wires, 225. 

Wires, Running, 225. 

H 

Hand Brake Mechanism, 123 to 125. 

Heaters, Electric, Car, Advantages of, 143, 144. 



362 INDEX. 

Heating and Lighting of Cars, 134 to 153<. 

Coils of Car Heater, 144, 145. 

High-Speed Service, 343. 
Horse-Power, 22. 
Horseshoe Magnet Core, 84. 
Hydraulic Circuit, 30, 31. 
Gradient, 44. 



Insulators, Strain, 235. 

, Trolley Wire, 235. 

International Unit of Activity, 23. 

J 

Joule, 18. 

per-Second, 23. 

Journal Boxes, 104. 



K 



Kilowatt, 24. 
Hour, 53. 



Lamination of Armature Core, 74. 
Lamp, Car, 136, 137. 



INDEX. 363 

Lamp Circuit of Car, 135, 

Lamps, Pilot, 284. 

Law, Ohm's, 42, 

Left-Hand Frog, 239. 

Lever Brake, 122. 

Lichtenfeld Railway Line, 13. 

Lightning Arrester, 201 to 203. 

Arresters, 266. 

Line Circuit, Efficiency of, 59 to 63. 

— or Circuit, Drop in, 54. 

Liquid and Electric Flow, Analogy between, 3 
to 7. 

Flow, Resistance of, 33. 

Load, 278. 

Diagram, 299. 

, Effect of, on Efficiency of Motor or Gene- 
rator, 58, 59. 

Locomotives, Electric, 323 to 342. . 

Lubricating Bushing of Trolley Wheel, 210, 211. 



M 

Made Circuit, 27. 

Magnet, Permanent Horseshoe, 83. 

Poles, Consequent, 90. 

Magnetic Blow-Out, 160. 



364 INDEX. 

Magnetic Circuit-Breaker, 269 to 272. 
Maintenance and Operation, 297 to 306. 
Maximum Traction Truck, 100. 
Mechanism of Brake, 122. 

, Trolley, 205. 

Meter^ Efficiency of, 57. 
Milliamperes, 276. 
Mining Locomotive, Electric, 341. 
Motor, Carbon Brushes for, 96. 

, Electric, 67. 

, Electric, Four-Pole, 88. 

-^ , Electric, Quadripolar, 88. 

Load, 170. 

of Electric Locomotive, 336. 

, Street Car, 67 to 96. 

Suspension, Method of, 111 to 114. 

Motors, Double-Reduction, 118. 

, Single-Reduction, 117, 118. 

, Slow-Speed, 118. 



Negative Plate of Storage Cell, 309. 

Ninth Working Notch, of Car Controller, Dia- 

gram of Connections of, 189. 
Non-Vibrating Filament for Car Lamp, 138. 



INDEX. 365 

o 

Ohm, 35. 

, Practical Definition of, 41. 

Ohm's Law, 42. 

Open Car Wheels, 107. 

Circuit, 27. 

Operation and Maintenance, 297 to 306. 
Output of Station, 299. 

P 

Page, 9. 

Panel, Pressure, 263. 

Panels, Feeder, 263. 

Parallel Connection of Street Cars, 187, 188. 

Permanent Horseshoe Magnet, 83. 

Pilot Lamps, 284. 

Pinion Armature, 115 to 117. 

, Double, 119. 

, Rawhide, 120. 

Pinkus, 9. 

Plate of Storage Cell, 309. 
Pneumatic Car Brake, 122. 
Points, Feeding, 65. 
Pole, 32. 

Climbers, 224. 

, Trolley, 205. 



366 INDEX. 

Portrush Electric Car Line, 13. 
Positive Plate of Storage Cell, 309. 
Practical Definition of Ohm, 41. 

International Unit of Activity, 24, 

Pressure, Back Electric, 47. 

, Back Water, 45. 

, Effective, 47. 

— Panel, 263. 

Pull, Electromagnetic, 84. 



Q 

Quadripolar Electric Motor, 88. 

Street Car Motor, 91. 

Quantity of Electricity, 42. 
-^ , Unit of Electric, 48. 



E 

Radial Truck, Action of, 101. 
Rail Bond, 246. 

Bond, Chicago, 246. 

Bond, Welded, 248. 

, Bonding of, 245, 246. 

, Continuous, 248. 

Railroad, Bicycle, 326 to 330. 



INDEX. 367 

Railway, Electric, of Berlin Industrial Exhibition 
of '79, 12. 

Lamp, 136. 

Rate-of -Doing-Work, 20. 

of Electric Flow, 28. 

Rawhide Pinion, 120. 

Resistance Coil for Street Car, 177. 

-, Electric, Unit of, 35. 

of Conductor, Influence of Cross Section 

on, 38. 

of Conductor, Influence of Length on, 38. 

to Electric Flow, 33. 

Wires, Effect of Dimensions of, on Resist- 
ance, 36 to 38. 

Rheostat Boxes, 265. 

Right-Angle Crossing, 240. 

Hand Frog, 239. 

Ring Armature, 75. 

Robinson Radial Truck, 101. 

Rope, Trolley, 205. 

Rotation, Counter-Electromotive Force of, 166. 

Running Guard Wires, 225. 



s 



Safety Fuse, 11, 198. 
Sand Box, 131, 132. 



368 INDEX. 

Second Working Notch of Car Controller, Diagram 

of Connections of, 179. 
Secondary Cell, 309. 
Segments, Commutator, 77. 
Self-Contained Electric Railroad System, 307. 
Self-induction, Counter-Electromotive Force of, 

165. 
Shunt or By-Path, 182. 
Siemens-Halske, 12. 
Single-Curve Suspension, 229. 

— Reduction Motors, 117, 118. 

Track Bracket Support, 222. 

Track Bracket Suspension, 223. 

— Trolley System, 204. 

Truck, 98, 99. 

Sixth Working Notch of Car Controller, Diagram 

of Connections of, 186. 
Skidding of Car Wheels, 129. 
Sleet-Cutting Trolley Wheel, 210. 
Slow-Speed Motors, 118. 
Snow Sweeper, Electric, 303, 304. 
Span Guard Wires, 225. 

Wire, 234. 

Wires, 219. 

Wire Support, 220. 

Wire System, 220, 221. 

Splicing Ea*i% 232. 



INDEX. 369 

Station, Output of, 299. 
Stationary Electric Motor, 87. 
Storage Battery Car Truck, 317. 

Battery System, Car Controller for, 320 to 

322. 

Battery Systems, 307 to 322. 

Cell, 309. 

Cell, Elements of, 309. 

Cell, Negative Plate of, 309. 

Cell, Positive Plate of, 309. 

Cells, Frame or Grid of, 314. 

Straight-Line Suspension, 227. 

Strain Insulators, 235. 

Street Car, Brush Holder for, 95. 

Car Motor, 67 to 96. 

Car Quadripolar Motor, 91. 

Car Resistance Coil, 177. 

Street Cars, Parallel Connection of, 187, 188. 
Strip, Commutator, 77. 
Support, Triple-Truck, 101. 
Suspension, Double-Curve, 229. 

of Car Motor, Method of. Ill to 114. 

— , Single-Curve, 230. 

, Straight-Line, 227. 

Switch and Cut-Out for Car Lamp, 139 to 141. 

, Automatic, for Car, 129. 

5 Canopy, 199, 200. 



370 INDEX. 

Switch, Emergency, 156. 

•, Temperature-Regulating, for Car Heater, 

147. 
Switches and Controllers, 154 to 203. 

, Feeder, 266. 

Switchboard, Railway Generator Statiori,262 to 266. 
Switchboards, 262 to 278. 
System, Feeder, 65. 
, Single-Trolley, 204. 

T 

Temperature-Regulating Switch for Car Heater, 

147. 
Tenth Working Notch of Car Controller, Diagram 

of Connections of, 190. 
Third Working Notch of Car Controller, Diagram 

of Connections of, 182. 
Three- Way Frog, 239. 
Total-Current Panel, 263. 
Tower Wagons, 2, 302. 
Track Construction, 242 to 248. 

, Double, 99, 100. 

Truck, Maximum-Traction, lOOo 
Tread of Car Wheels, 109. 
Triple Truck Support, lOlo 
Trolley Base, 205. 



INDEX. 371 

Trolley Base, Boston, 214, 215. 

Base, Forms of, 213 to 218. 

Crossing, 239. 

Ear, 227. 

Frog, 237. 

Insulator, 227. 

Line Construction, 219 to 248. 

Mechanism, 205. 

Pole, 205. 

— Rope, 205. 

System, Conduit, 306. 

■ System, Underground, 306. 

Wheel, 205. 

— — Wheel, Forms of, 209. 

Wheel and Harp, 208. 

Wheel, Lubricating Bushing of, 210, 211. 

Wheel, Sleet-Cutting, 210. 

Wire Insulators, 235. 

Trolleys, 204 to 218. 
Truck, 85. 

, Robinson Radial, 101. 

Twist, Electromagnetic, 84. 
Two- Way Frog, 237. . 

u 

Underground Trolley System, 306. 
Unit of Activity, 21. 



372 INDEX. 

Unit of Electric Current, 28. 

— of Electric Quantity, 48. 

of Electromotive Force, 32. 

of Resistance, 35. 

of Work, 53. 

Y 

V-Frog, 237. 

Vanderpoele, 13. 

Voltmeter, 54, 263. 

for Railway Switchboard, 274 to 275. 



w 

Wagons, Tower, 302. 

Watermotive Force, 31. 

Water-pipes, Resistance of Flow through, 33. 

Watt, 23. 

Watt-hour, 53. 

Watt-hours of Storage Cell, 310. 

Weight of Electric Car, 298. 

Welded Rail Bond, 248. - 

Wheel, Trolley, 205. 

Wheels, Flattening of, 131o 

, Tread of, 109. 

Wire, Span, 234o 



INDEX. 3 i 3 



Wires, Guard, 225. 

, Span, 219. 

Work, 17, 18. 

— '■ , Unit of, 53. 

— , Units of, Ifo 



NOV 5 1906 



